That's something I would be interested in, too. LOS 17.1 was painless for me so far with OTA updates – but then again it was non-rooted, no Magisk, just LOS + Gapps.
Now that today one of my mandatory banking apps (mandatory even for entering internet banking on the PC) has stopped working, complaining about a modified software/firmware, I'll need root plus the stuff that hides both root and the fact that it's an alternative ROM rather sooner than later.
I guess changing the update procedure to sideloading the updates like @Hook has been doing would be ok for me, although I'd be even