This thread seems to be turning into a blog of my attempted change.
If the moderators prefer a different approach – or none at all – please let me know. Having said that, this may be of general interest. I think my configuration is fairly typical, at least for any who started with the RL + Plasma ISO.
FWIW, just a reminded that I attempted to migrate from Plasma to Gnome because of the missing “breeze…” asset that blocked the v8.5 update. I thought that was Plasma-specific – perhaps not.
I’m now doing the suggestion of @tjdoyle of going back to sddm (instead of gdm).