From what I have found out from TheKit is that most parts needed for voLTE are merged but have not reached 20.04 Devel yet. When volte is working there may still be an issue with the x23 in the USA may well be the bands and the up coming Quintus may be a better option.

When will there finally be a subcategory for the volla x23? The device has been around for a long time now.