> I have tried “Fractional Scaling” – it works OK on Wayland, but leaves all the fonts looking soft and fuzzy.
Ah, there we go. The real, underlying problem is that the scaling that would make this problem go away doesn't work for you.
Scaling the fonts instead of fixing the underlying issue and then deciding that all of web development is wrong for optimising for CSS pixel count (like one should) instead of manually doing DPI calculations (which everyone gets wrong, very often, and probably Javascript just to do a basic layout) is a silly solution.
Look for a blurry-font-rendering solution instead of a change-the-way-everyone-develops-websites solution, it's a lot easier to convince people that it's a real problem.