I’ve been looking across the internet, up, down, front, and back. No clue.

Let say two artists put their work together and want to add a donation banner on the webpage of their collaboration. For example, a singer shares their music with a video maker.
First, they agree on an arbitrary share for future donations. Like 50%/50% or 75%/25%, etc.
They may not know each other well, they may live in two separate continents.

Is there any platform or api allowing this?

• Once the share is agreed upon, an artist can not change it without the approval of both.
• The platform shouldn’t be bound to a country (for example Stripe cannot accept international donations, unless the artists are in the US).
• I may be wishing for Santa Claus, but a privacy-friendly solution would be awesome.

Any idea appreciated, I’ve been drying my a$$ off for weeks on this one.