You might want to check out Brave [1] which does pretty much exactly what you described:

> Set up automatic micro-donations. Brave will automatically divide a monthly donation among the top sites you visit.

See also their blogpost about it [2] and the FAQ [3].

[1]: https://brave.com/ [2]: https://www.brave.com/introducing-brave-payments/ [3]: https://www.brave.com/faq-payments/