Font rendering has kind of stopped sucking on Linux lately. There was this guy making a package called Infinality which majorly improved the appearance of most fonts on Linux. His patches has fiiiinally been pushed upstream to fontconfig and freetype2 themselves.

But that's not the major difference between Android and Linux -- it's the DPI. Mobile phone screens have about four times as many pixels/unit of area compared to regular 1920x1080 screens. Run Linux on a HiDPI screen and fonts will look just as good.