it really is only Samsung. Any Qualcomm SoC past 2020 won’t cause an issue. Murena did do some outreach to get VoLTE freed on Samsungs (the phh-ims work), but it didnt seem to have left the proof of concept stage.
Doing the smali patch method per device is imo the most promising, but involved route.
Also someone packaged the ims work of phh recently to be more easily integrated at amikhasenko/ims - the status is working outgoing calls, incoming drop after accept. It’s geared to the A21s though with a small binary patch (as is the jameskdev work) and LLM help on the reverse engineering.
In general, following the latest entries in this xda thread keeps people updated.