Proton passkeys are stored in a password manager, which he specifically calls out.

If you have a password managed and know how to use it, you’re already a lot less susceptible to the problem that passkeys are trying to solve.

Personally, I think passkeys are great for tech-savvy users, but I wouldn’t dream of recommending them to non tech-savvy people. Password managers are still used by the minority, that needs to be fixed before passkeys are useful.

Linux mint is a pub of some type of some type of some type of…

You’ll find that under settings -> customise -> swipe address bar sideways to switch tabs

Changing your user agent will not stop you being tracked. Browser fingerprinting can work with heaps of different signals, and is very difficult to block.