This list is missing a linux-ey system which doesn't use Systemd that is growing in popularity!

WSL!

WSL somewhat annoyingly has a custom/proprietary init system. Partially due to it's "interesting" integration with windows, and partially because it's not even really a full linux system yet.

I'm curious if with the switch to WSL2 where they will begin shipping a full linux kernel if systemd will be included or will they stick with their current custom solution?