The others phones that I know of:
Xiaomi Redmi Note 9 Pro - sounds like VoLTE is working for people, but band compatibility may not be perfect.
Xiaomi Poco X3 NFC - ""
Various Volla - ""
I've heard of people in USA using all three of these, but you really need to do your research and check with mobile providers.
Brax 3 has a UT port that's coming along. Applee has been in touch with them. It seems too early to say though, which is too bad, because they have a December shipment coming along.
Similarly Furiphone talked in the past of a UT port, but I haven't heard anything about it in a while. Both of those are explicitly made to work well in USA (among others).
Also Fairphone 4 is supposed to have working VoLTE now? There was an ebay seller in USA who was selling Fairphone 4 new. NeverMSRP I believe.
Ruben continues to work on VoLTE on the Oneplus Nord N10. Crossing fingers on that. Some people already have good results, but he's clear that it's still wonky so far.