Yes, since installing eOS q see here.. Previously I had flashed stock Android 9, booted it and used it with my SIM inserted, noted that wifi calling was working and taken screenshots of the APN details. Sim is from 3 UK.
My XA2 is now on e-0.18-r-20211005139260-dev-pioneer. I no longer use it as daily, just testing, and I feel that battery life has not changed and is still good for me.
As for the versions; there are numbers and letters.
Letters are the main android OS version such as n, o, p, q and r , upper or lower case no different. Sometimes referred to as oreo, pie and I don’t know what else!
The number is the e release number that can apply to any of the versions. If you see a reference to eOS 0.18 that only tells you it is fairly recent release but it does not tell you to what android version it is intended. eOS-q tells you it is android q/android10.
What are you running on your device at the moment? Is it the pie test build?
OTA updates on XA2 are only possible for the same android version as that which you have installed.
OS upgrades, to Q or R have to be manually flashed. Clean install is usually best so you would have to back up what you can and start again. Now is a good time to move to R as it is new for e.
Also the phone should have been on stock android 9 at some stage before flashing.