Safari 15.4 and later supports manifest versions 2 and 3. [1]

Mozilla maintains a list of which keys are compatible across which browsers as well [2]

[1] https://developer.apple.com/documentation/safariservices/saf...

[2] https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/Web...

good to hear, thanks for the resources. Do you know if Apple has made any specific statements or commitments to continuing to support v2 for the foreseeable future?

There were no official statements, but an engineer at Apple working on extensions said that "Apple sees extension APIs as long term support".

https://github.com/w3c/webextensions/issues/298#issuecomment...

Relax, sure it’s self promotion, but they are the author of the TFA so it’s not like they’re jumping into a random thread.