I really don’t think that’s a good idea.
What if someone puts their game as -0.50$ and accidentally put it live, and suddenly a million users download it. Will they go 500.000$ in debt?
What if someone downloads your game but doesn’t give you any feedback at all, just for the money?
If you are prepared to pay for playtest, it’s better to find specific playtesters, pay them individually and give them a copy of your project for free on Itch. There’s probably some site dedicated to it, but I’m not really familiar with any.