Right now - easy, with the difficulty going up over time as the main Chromium codebase continues to change (and especially as it gets security updates). I think I’ve read that some variants (Brave?) have committed to supporting ManifestV2 for as long as possible, for instance with their own fork.

All that yes. The Wooting One (original that uses IR light) let you use buttons to simulate controller axes, change how hard you need to press to activate, and add second functions to keys. It was an interesting idea but I found the gaming part the original keyboard to be only usable in a limited set of games as it’s not as sensitive as a controller stick, and as a keyboard it wasn’t great either. Hopefully V1 problems, I know they had through another version of the IR keyboard, and then came out with the Hall effect keyboard. I like the idea but never could get used to it, and when the spacebar was loose I retired it after fixing it.

apropos to search man pages, otherwise I use man