I can't say that the feedback causes damaging levels of noise, and its possible that my hearing is still protected, but the feedback that is produced is so uncomfortable that I involuntarily pulled them out of my ears.. which is not a great reaction with power tools in hand.
Apple does market 'Hearing Protection' as a feature of the AirPods Pro. https://support.apple.com/en-us/120850
Looking at the ANSI Datasheet, it seems like it's not really suited to the sounds coming from all power tools since they can reach or exceed 110 dBA:
> The Hearing Protection feature is not suitable for protection against extremely loud impulse sounds, such as gunfire, fireworks, or jackhammers, or against sustained sounds louder than 110 dBA.
I suppose if you know your tools operate at 110 dBA or lower levels, you're good to go. The feedback is bizarre though... Hopefully Apple resolves that with a firmware update!
Edit: It looks like it can safely attenuate sound at 110 dBA for 16 to 63 hours. That's impressive!