Have you looked at SimpleX Chat? Totally private and decentralized (the infrastructure is similar to nostr), no user IDs of any kind, including no phone numbers. SN even has a chat that you can talk to them on. It's a really good option that I'm sure many people around here would endorse.

I still use Signal in some cases, just because SimpleX doesn't feel quite polished enough for my family and friends to get into it yet, but it is definitely a project to look into friend