This is unfortunate, since many applications can scale just fine, but only through older hacks. Chrome and Electron applications will scale just fine by providing a proper DPI. Same for very old apps. GTK and QT applications will not, but they scale just fine by setting appropriate environment variables.
In practice, this leads to the experience often being better on X11. I've found KDE X11 to handle this the best, with the limitation being a single global scale, only certain fractions allowed and needing to restart KDE after changing it.
GNOME with Ubuntu patches and Xfce will scale everything x2 and use RandR to provide a higher virtual resolution. This has performance costs and messes with cursor speed (measured in pixels) but otherwise also produces good results.
[1] https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests...
Also, there is some ongoing work on Wayland in Java - https://www.phoronix.com/scan.php?page=news_item&px=Wakefiel...
The cases where fractional scaling doesn't work on Wayland are when you're running an app through XWayland. In those cases, I'd just find an alternative that works with Wayland. That's also what lead me to switch to Firefox full-time - Chromium's Wayland support lagged behind quite a bit.
What's also kinda sad and funny is that X11 has had from day 1 support for different DPIs on different displays. But most programs just ignore X11s DPI setting and assume it's 96ppi. It also conflicts with modern multi-monitor on Linux which essentially fakes one giant display so you can drag windows across. There is some drawbacks but if you config each monitor to be a separate X11 display with the proper DPI and use compatible programs like Alacritty it kinda just sorta works.