Just put it out in the real world via the app stores.

This provides a chance to solve all the problems that you are trying to avoid like app approval, marketing, customer service, etc. etc.

It is a good filter on whether or not you are sufficiently motivated to deliver. There's nothing wrong with not being sufficiently motivated. And it's better to discover that sooner rather than later.

Yes. The best platform to demo your prototype to billions of users is something special called the Web. You might not have heard of it, but it's thus thing that's been around for decades. In order to access the Web, you will need internet access. If you have any difficulty with the instructions, post your replies in this thread.