How big of an issue is VoLTE to degoogled Android phones?

Question

Networks are switching to VoLTE soon. It seems that carrier and phone compatibility for GrapheneOS and LineageOS is either extremely limited or not documented.Are there any resources for this? How are potential users going to use things like GrapheneOS or LineageOS? This seems like it could be an existential crisis for these projects if many phones will be unusable in a few months and there's no information about combinations that work.

giantg2 · Accepted Answer

Just to add, I'm looking to switch to GrapheneOS or LineageOS and this is a huge blocker for me.So far, the only combo I see that will definitely work is a Pixel line phone, GrapheneOS, and Tmobile. I'm not a fan of the Pixel's short-ish battery life, the phone's price, and Tmobile is 2x my current bill. I would really like to know my other options.