@Tobias-Schimpf I've been running focal on my Volla Phone X for some time and have just updated to OTA3. It runs OK but the battery life is reduced on Focal, on Xenial I could just about go three days between charging, now I have to charge every day (mostly twice a day).
You could get it by changing your channel in settings but the advice appears to be to do a conplete reinstall (with wipe user data) from the installer. I just noted down all the contacts and re-entered them after the install. I also backed up my data and copied my photos across.😇