Sharing this blog post because I liked reading it. Nice photos and images and shows lots of options. The section about Gentoo Linux suggests it is unclear whether Gentoo uses Systemd. From what I’ve seen after tinkering with a Gentoo container last week is that Systemd is an option for “make world” but not the default.
https://blog.darknedgy.net/technology/2020/05/02/0/ this blogpost is a nice technological and historical overview. Systemd is sometimes good sometimes bad and sometimes ugly (for the love of God I cant make resolved work and the documentation just isnt there). At the end of the day if it works for you don’t fix it but just for the sake of it I would recommend trying out another init system and seeing for yourself