It's easy to transition a windows user to Plasma as their underlying concepts are very similiar in how windows and workflow are organized. And you can set it up to look exactly like Windows, which would reduce pushback/confusion by the users.

I had one person convinced the laptop I gave them was a Mac for several week. I mean an experienced user would notice things after a short while, but it took quite a while for this user to catch on, and when I told them they were on Manjaro (which they have no clue what that is), there was a shoulder shrug and carried on. Apps like WPS Office look different, but not all that strange.

A basic KDE desktop is as lightweight as XFCE in my experience. You can load it up if you try hard enough, but they've put a pile of work into keeping things light and snappy.

Kasm is pretty neat. I run it as a docker stack on it's own VM, it's getting quite decent from a sysadmin standpoint since that's a heavy focus of theirs for setting up a Linux based VDI.