My OnePlus 6 running Kupfer (Arch Linux ARM) [0] and my Shift6mq running Mobian [1] (Debian blend) in dual boot from microSDXC card [2] would like to have a word. Droidian (Halium-based Debian) also supports the enchilada.[3]
And then, there's also NixOS mobile [4]. They all have had systemd before this.
[0] https://kupfer.gitlab.io/, setting up kupferbootstrap can be hard though, especially if you don't have docker set up on that system already.
[1] https://wiki.debian.org/InstallingDebianOn/OnePlus/OnePlus6 To be frank though, I failed at installing Mobian on sdm845 hardware earlier myself, too.
[2] https://wiki.debian.org/InstallingDebianOn/SHIFT/SHIFT6mq#In...
[3] https://devices.droidian.org/#/devices/enchilada
[4] https://mobile.nixos.org/devices/oneplus-enchilada.html