I just released Seedfiles v1!
It's a portable drop-in reimplementation of systemd-tmpfiles, I already managed to replace systemd-tmpfiles on my Gentoo installation with seedfiles and it just works
Gardenhouse news item: https://gardenhouse.pinkro.se/news/seedfiles_tmpfiles_reimplementation.html

Seedfiles source: https://git.pinkro.se/Rose/gardenhouse/seedfiles.git/about/ / https://codeberg.org/axtlos/seedfiles