I'm using a 4k screen with my sway tiling desktop. Enlarge the fonts from alacritty and emacs, set fractional scaling to 1.5 from Firefox and you're done.
Except that Xwayland applications are either tiny or scaled up and blurry. I guess it's acceptable if you have a large (e.g. 30") screen. But on a 24" 4k screen both options are very unpleasant.
Also, I don't think Sway is an alternative for most macOS desktop users.
I'm an old macOS user. I downsized what I need from a desktop and I'm very happy with my minimal setup.
I'm not using scaling from sway/wayland, but I basically just use emacs, firefox and alacritty, so changing those apps is all I need to do to get scaling done.
Also, I don't think Sway is an alternative for most macOS desktop users.