Have you tried Plasma on Wayland? I've found it has very good fractional scaling support, better than Gnome or Windows. I don't own a Mac so can't compare to MacOS, and haven't used X in years, but fractional scaling with Plasma has been problem-free for me. No weird window resizing like Windows does, no blurry text, just everything on different resolution monitors staying the same visual size.

Your scaling with the Plasma compositor implementing the Wayland protocol will depend heavily on the graphical toolkit the specific application is using. Gtk vs Qt vs Flutter, etc. Each of these has to implement custom backends for the waylands and that work is far from done re: fractional scaling. And each wayland compositor is quite a bit different too since the core wayland protocol is so slim and each has to implement core features their own way.

Whereas there's just one thing to target with X11. Far more consistent, less buggy overall. At least up to now. But with megacorps like IBM/Red Hat having their employees abandon X11 entirely for Gtk5, etc, it's gonna be rough going everywhere.

I haven't. Thanks for the suggestion, I might give it a go. I returned to Linux this year, after 10 or so years of Windows. My hope was in 2025 we have reached a state where you can install a distro and be done with it. Seems like endless hours of tweaking are still required :(