Most people use Xbox, PS4/PS5, Switch controllers.
Those all have perfectly mapped inputs on Chrome, so they're consistent. (Firefox isn't as good here as my bug report above shows.)
And I'm guessing popular alternatives like 8Bitdo and Logitech would also be mapped, but I haven't got them yet.
But yeah a lot of the other generic ones like the PS1 or N64 controllers on Amazon, do not have proper input mappings yet.
For Angvik 2, what I did was manually create an array of button inputs for many cheap no-brand controllers. I would use the gamepad ID string to detect which controller was being used. Basically making my own personal database of controllers. This way I could have heaps of gamepads that are usuable for my game, and they'd work by default.
Some years ago, I think I may have reported some controllers to chrome and it got mapped, but I can't remember why I stopped doing that.
Perhaps I should try submitting an issue to Chrome again, and see if they'll add more controllers. This way we can all benefit, having controllers work properly and easily for everyone.