I've helped 500+ founders get out of their heads and start building confidence in a few key areas: crowdfunding, fundraising, and early stage growth. I'll be a sounding board, voice of reason, and devil's advocate as you pursue your next steps, and you will leave our call with actionable direction to keep moving forward.
Your first step should be finding someone with experience in hardware and getting their insight into the feasibility of your product. That person will need to give you a sense for how unique your product is compared to what already exists, if it can be made with current manufacturing processes or needs something custom, and how much it would cost you to develop a prototype and a final version ready for market. You may find that you can use existing processes or technology to create something simple on the cheap. Or, it might be really complicated and expensive, which means you may want to look elsewhere for product ideas since the path to market with hardware is typically quite a bit more expensive than with services or software. You really want to know what you are getting yourself into with your specific product before you spend money on developing a prototype.
I'd also suggest researching similar products (or products that have a foundation in similar hardware technology but are in different form) to see how much you can reverse engineer when thinking through how your product will be made. Look at their costs, price points, and demand, and see how they compare to what you want to build.
Best of luck!
Many founders tend to view a product launch as a red carpet event that will get a ton of press coverage and huge social pickup. This isn't the case with 99% of companies. I've worked with hundreds of founders who expected a HUGE launch without testing product or building a set of customers ready for the product - only to find that most launches are inherently pretty uneventful. It's important to stay level and keep expectations for launch realistic, then build on what you learn and continue to grow your audience. The goal isn't to get an arbitrary number of customers on day 1 - it's to build a sustainable product with an audience that you know wants to buy it.
You can look at this two ways.
1. It doesn't really matter that your friend wants to launch the app, because the audience at launch is probably relatively small. You can use that audience to get feedback on it like you would on an MVP anyway.
2. if your friend has a big following around previous app launches, and launching a new app to that audience is a make-or-break scenario, then absolutely test with a portion of that audience beforehand. You can call them VIP's and give them early access, then hopefully count on them as your biggest supporters as you roll the app out to the larger audience. This gives you insight and gives them a feeling of exclusivity.
The equation of time vs. money is an important one. You don't want to sit on the app making changes for months, but you also don't want to come out guns blazing with the wrong product. Finding that balance is the most crucial point in your launch, and if the stakes are high with a big audience, definitely test it first. If the audience is small and can help give you feedback on the product, then a launch event probably won't have the potential blowback you envision. Best of luck!
The DIY startup method - build an audience around an area of your expertise, deliver that audience content they care about, then engage them to see what product of yours they would be willing to buy. Tim Ferriss (FHWW), John Lee Dumas (EOF), Bryan Harris (10KSubs), and countless others have taken this approach and turned out scalable businesses. It's great to have an idea of what visitors may want to buy, but the minute you build product before you build an audience for it, you immediately risk taking the wrong path at the expense of time, money, and momentum.
Even without knowing your industry, how you engage your visitors should be the biggest piece here - it's great to bring a bunch of people to one place, but if you aren't getting their contact info and making them stick around with content, discussions, videos, emails then it's going to be much harder to bring them back, let alone get them to buy from you. This can be as simple as blog posts, as timely as real-time video webinars, or as easy as delivering curated relevant articles via email. The end result should be you as founders and/or your site being seen as the best place to get information your audience cares about.
If costs to you are low (negligible, or easily offset by adding a small revenue stream), and you have the ability to deliver a knowledge base to your audience around your expertise, then go for it! The right level of engagement with that audience should give you some great insight into what they would buy, how much they would pay for it, and how likely they would be to share their experience with others. It can take a few shots to find the right balance of product vs. demand, but having that knowledge base and content allows you to be flexible in your approach. Don't assume you know what your visitors would buy - test your assumptions by simply asking them. Get an understanding of the biggest questions they want answered, answer them through content, and use this insight to build product. There is no 'right number' of visitors - even getting 100 email addresses can be a huge start to understanding what to build.
The biggest mistake I see startups make is attempting to scale a product before validating the direction that their customers want it to go. You'll see companies validate pre-launch via closed beta testing, crowdfunding, or building landing pages and testing everything from messaging to price point to conversion funnel. Given that it seems like you're already doing some of this testing, I assume you've got a good handle on your options here.
The challenge is this: looking for the 'perfect fit' is an incredibly easy way to justify never launching a product, and launching too early is a surefire way to spend your first few months scrambling to figure out why people aren't buying your product like you assumed they would.
Launch when you are sure you've got a core set of customers that will buy your product. Don't wait for the 'perfect' moment - get it out to these customers as early as is practical (even earlier than you probably think) and use them to test your price points, messaging, and product fit.
Scale when you know what is driving them to buy, the price they are willing to pay, and how much it costs you to bring them on board. The numbers that drive this decision vary for every company based on product and industry - if you're selling an online course for learning jiu jitsu, your optimal rollout is going to look much different than a consumer tech product. One thing holds constant - to scale, you need a repeatable process that you know will drive conversion and customer acquisition while keeping your costs at margins that make sense to your business.
Questions I would make sure I can answer between launch and scale:
1. Can you say for certain that you know what customers are willing pay? It's great if they are paying $79, but do you know if those same customers would pay $99? What about monthly vs. annually?
2. Do you know where to find more of these customers in large numbers, and how to drive them to your site/product? If so, how much will it cost you to access these customers?
3. When you do drive them to your site/product, what percentage indicate a level of interest (giving an email address, signing up for your platform, getting on a pre-order list)? What percentage click with an intent to buy right away?
It seems that you're already doing the right things by testing your product first and exploring next steps with an intelligent outlook. Keep that up and you'll continue to make decisions that move you in the right direction.