Linux builds are up to distros to build and package (or do it yourself). We don't have the manpower to cover the 100+ distros under the sun due to Linux NIH syndrome. As long as alpine basically supports a full desktop environment using wxWidgets, it should build and run just fine.

Out of curiosity why would they create a distribution for Alpine? At least in practical use I don't know of anyone who uses it as a desktop OS like other distributions. I don't know of any features of KiCad that make sense when you don't have a solid UI (I also imagine that most users of alpine are sufficiently advanced to just compile it themselves if the rest of the dependencies are there).

The Arch Linux PKGBUILD (https://aur.archlinux.org/cgit/aur.git/tree/PKGBUILD?h=kicad...) doesn't look too complex, you could try building from source. Neither `opencascade` or `ngspice` look like they're packaged for Alpine, so you'd have to build those from source first. I don't know how complex that would be. Off the top of my head the rest of the dependencies are already in the alpine package repos. Building from source isn't as hard as it's reputation. Most of the time it's just a `autoconf -i && ./configure && make && sudo make install` tbh. Just do a cursory read of the README, and `./configure --help` first.