It does yeah, but not for applications running in XWayland. For example, I'm running a secondary 4k monitor with 1.5x scaling so it matches the other 1440p monitor. For native wayland applications, everything works just fine, but running an XWayland application on the 4k monitor will make it render at 1440p and become a blurry nasty mess. In KDE it will render in proper 4k (as if it was native a Wayland window), because they've somehow worked around that issue.
AFAIK wlroots does support fractional scaling since Feb 23 https://www.phoronix.com/news/Sway-wl-roots-Fractional-Scale
It does yeah, but not for applications running in XWayland. For example, I'm running a secondary 4k monitor with 1.5x scaling so it matches the other 1440p monitor. For native wayland applications, everything works just fine, but running an XWayland application on the 4k monitor will make it render at 1440p and become a blurry nasty mess. In KDE it will render in proper 4k (as if it was native a Wayland window), because they've somehow worked around that issue.