I'm also a Plasma user, and I decided to try it out in a vm yesterday after reading this thread. It didn't appear to play nicely in a vm. It was honestly the weirdest thing. Lots of freezes in my plasma session. Not the only distro that has problems in a vm, but still unexpected.
Anyways, there were a lot more packages for it than I initially thought. However, still lacked some things that I wanted to use, and like nixOS it seems different enough that I would need to put in a bit of work to get those things working on alpine.
I have heard good things about how openSUSE handles it.