And it's not even that difficult to build good bitcoin support into a chat app. I'm a relative noob to privacy tech and - thanks to good existing libraries and AI assistance - I was able to make a chat app with a cashu wallet built-in, using the MDK (Marmot Development Kit) for MLS chat. I don't expect to continue on my project, it was just a fun project to get to know the libraries, and to learn how things like push notifications work and to learn more about MLS.

I hadn't heard of Keychat, I'll check it out now!