The best way to validate a idea is by doing it. So just do it. People should be shipping prototypes every 2-3 weeks. It shouldn't take you that long. Even if you're slow, you're shipping at latest in a month.
Could you maybe share some platforms with TA where I could test my prototypes?
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.