If it bothers you enough "to switch", that implies you've not been writing extensions using universal web extension code, in which case.... what? Why not? The only massive difference is the namespace ("broswer" vs. "chrome"), which is trivially shimmed, and promises vs. callbacks, which is also easily made universal.

But having said that, if you're considering switching you probably also want to consider telling your paid customers how to install your extension themselves, rather than sending them over to Google's extension "store".

Probably, but browser extension developers need to go where the users are. Google has leverage and knows it.