I would suggest recording yourself using different microphones and comparing them to see how bad Airpods mic is.
I suspect it's because the wired earbuds had a mic near my throat whereas the Airpods' mic were up near my ears. The difference is very noticeable.
Looks like I'll be keeping my wired earbuds around for future conference calls.
So, either you'll get a lot of ambient noise, the signal is quiet or Apple will do some algorithmic trickery that tries to approximate some kind of echo cancelation on the audio signal, but compared to a simple dynamic microphone that just has a more favorable position and form factor, it'll always lose.
Also, it's worth noting what the goal is here. The aim is not to capture the most accurate sound period. I've had calls with people who clearly have very expensive setups, but I end up hearing pen clicks, keyboard sounds, breathing, swallowing etc. The Airpods seem to do a great job of making my voice sound good in general. I've gotten compliments on my audio (so it can't be that bad) and the Airpods don't seem to pick up my breathing, typing, etc so I'm happy.