ChromeOS also does fractional scaling properly because Chrome does it properly. The scaling factor is propagated through the rendering stack so that content is rastered at the correct scale from the beginning instead of using an integer scaling factor and then downscaling later. And it takes subpixel rendering into account too, which affects things like what elements can be squashed into layers backed by GPU textures.

I think Android does it properly too because they have to handle an entire zoo of screen sizes and resolutions there. Although they don't have the issue of dealing with subpixel rendering.