https://wayland.app/protocols/fractional-scale-v1
Also, I wouldn't hold the rendering quality of macOS as a high standard at all, since all it does is render at a multiple and then downsample, wasting energy and introducing blurriness.
Contrary to Windows, this also works well when hotplugging screens. Menus don't end up a blurry mess, and apps seem to work fine. On Windows, even some 1st-party apps are borked (task manager comes to mind).
As the other comment says, I suspect it to do with GPU as the built-in displays are usually driven by intel and external displays are always driven by my Nvidia 4090.
But surprisingly, when I drive my e-paper monitor using original Jetson Nano (Ubuntu 20.04 ESM / Nvidia Maxwell); the fractional scaling is quite good perhaps even better than macOS.
Gnome >= 47 is fine, you will need to do:
`gsettings set org.gnome.mutter experimental-features "['scale-monitor-framebuffer', 'xwayland-native-scaling']" ` That stops being necessary as some point around 49/50 I think.