Well, before wayland I always used fluxbox (eventually with picom compositor, which previously was compton). Then now on wayland I’m using sway with fuzzel, yambar and others.
I’ve always felt both gnome and kde, as well as most other DEs really bloated. Gnome used to be more stable on wayland, and as of Today with better support for nvidia AFAIK, but KDE is quickly catching up.
Not sure why the hate on gnome (and I guess on GTK as well). It doesn’t offer all the customization by default, but you can get it through extensions while available. But on KDE one really needs to see a pletora of dependencies each time one adds a simple module or application. Both are improving gradually to become less intense on resources being KDE more advanced on that.
But hey, both are bloated compared to non full DE compositors such as sway or labwc. BTW I use sway with tabbed mode (not actually tiling) and some tweaks, and I prefer that over stacking compositors, but if wanting one labwc is pretty cool.
On X11 there’s a huge amount of window managers plus compositors plus several other applications which altogether can give a similar sense to a DE but way less intense on resources, and for sure way less bloated. To me DEs are overrated to answer your title, but perhaps that’s just me, :)
Guix is source base rolling release if you plan to keep it up to date weekly, so I don’t know why you feel it so distant from Gentoo. Binaries updates are still rolling released but their pace is slower.