Wayland by itself does not* support fractional scaling out of the box, or at least it didn’t until November of 2022 when the prerequisite protocol extensions were merged to the project.

And AFAIU clients (applications) still need to implement this protocol. Something like wxwidgets or old gtk versions probably won’t ever get to implementing it.

* Some compositors employ some workarounds to achieve this, like the scaling tricks where they render to a larger buffer and then downscale it…