I would like to implement a system in my app that allows one user to buy a digital product from another user. See this as an event ticket reservation system. The organizer is the seller and the final user is the buyer.
I would take a little fee to make it profitable.
Are those kind of payment subject to 30% commission from Google?
Do you know a secure system (PayPal maybe?) that could help me to set it up?
Apple or Android in app purchases can be only used in conjunction with use cases defined by developer agreement.
All purchasing using an app is subject to the 30% fee, except for very specific use cases (like newspaper media subscription, etc.).
User-to-user real money transfer is a very tricky concept (as it basically allows funds transfer between individuals and tax and other authorities would want to control that) from both a legal and accounting points of view.
Unless you have serious business and you are willing to spent considerable resources to validate all nuances it is generally not a good easy idea to go with for an independent developer.
You can check Stripe Connect as the closest offering for web projects: https://stripe.com/connect
But also see their limitations section to see if it is even suitable.
