I've concluded that the AirPods or other products with consumer type noise cancellation, are not suitable for certain types hearing protection.
They are very good at reducing constant sounds. However in my case I tried to use them for two things and failed both times.
1) Musician earplugs at gigs
2) Wind noise protection on motorbike
1) Failed, because by nature the sound at the gig varies a lot and cannot be easily tracked digitally by the product. Also, (I'm a singer) my jaw and ear canals move, affecting the fit of the plugs. The effect was the noise cancellation does not track consistently or quickly enough. You hear a mostly quiet sound, but sometimes there are random peaks. Also, I believe there may be a constant stream of other (inaccurately tracked) high level sound (at the same level you are trying to block), sometimes outside the hearing range, but still damaging.
2) Wind buffeting noise is a perfect example of difficult noise to cancel, for exactly the same reasons as above.
Final result :
It's hard to know for sure, but I felt my tinnitus definitely spiked after practicing singing with the AirPods in a loud studio, and also riding the motorbike using the AirPods under my helmet. to reduce wind noise.
The spiking of my tinnitus was far more pronounced than I would have expected from the perceived sound level I experienced (which seemed very quiet).
AirPods with ANC would be great in situations where the noise is not above the safe 85db level and you just want to reduce it for comfort. Ie. on a plane or train.
This is just my own unscientific test and opinion of course, but I feel the basic logic is correct.