1: Chrome/Chromium will be both be affected as they are using the mainline release process, different browsers are taking different steps for them, for example Microsoft's is
here.
The important thing to note is that other browsers will eventually all break
once they have updated to the version which is actually affected, as an idea Edge has not accepted Manifest V2 submissions to it's page since 2022, so the next step is inevitably within the next few months.
2: The latest release of Chrome Canary has the policy for disabling MV2 enabled, so presume
from that release build regarding stable.
Cheers,