One of my friends spent like a month distrohopping just to find a debian-based distro that fits these two criteria:
First-class support for KDE
Isn't broken all the time
Ubuntu fails both. KDE Neon excels on the first one, but fails harder than ubuntu on the second one. Kubuntu as well. Debian has horridly outdated packages, and he refuses to use nix/flatpak. Tuxedo OS is obscure and broken. Mint is great, but installing KDE takes some effort.
He finally settled on Ubuntu Server with the native KDE package. Still has to do some weird incantations to banish snap tho.
He really insists on debian-based, I don't really know why. And, while Void IS really solid, it isn't exactly known for the most expansive package collection. Xournal, for example, is not available through XBPS (there is a xournal package, but it just installs xournal++), which is one of the programs he likes a lot. I told him it's on nix, but he doesn't want to use nix.
But I agree, Void is amazing, I use it on my laptop. One little-known cool feature of Void is that its official docker images come in busybox/musl libc, busybox/glibc, and coreutils/glibc variants, it gives you a nice scale from most minimalist to most compatible.
He could make his own templates for the packages... he doesn't even have to rebuild. If he could at least find a .deb or .rpm package of the app/package he likes, he could use that and just repackage. That's what I do for stuff I can't find... and update them from time to time (like every few months or so).
I'd love to know what's consistently breaking on KDE Neon for you. I've got some specific bugs I'm working through with their team, but I've never found it to be "always broken" (although I will say it is easier to break than Kubuntu IME).