I would think the best workaround (until carriers/handsets fix this) is to change your cell network - which you can also do if you have poor signal in an area:

I would think the best workaround (until carriers/handsets fix this) is to change your cell network - which you can also do if you have poor signal in an area: On iPhone, go to Settings > Cellular > eSIM name > Network Selection and turn off “Automatic”. Then pick a different network. Admittedly, this is neither fast nor easy/intuitive. As pointed out in a sibling comment, the fault lies with Apple and Google for not forcing the 911 call on a different network after it fails. The fix carriers are discussing sounds like finding a way to re-route 911 calls over other networks on the same tower, or some other failover mechanism. It’s not clear if that would be simpler than having a handset try again on a different network.