- https://systemd.io/
- https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/9/html/using_systemd_unit_files_to_customize_and_optimize_your_system/assembly_working-with-systemd-unit-files_working-with-systemd#con_introduction-to-unit-files_assembly_working-with-systemd-unit-files
- https://www.freedesktop.org/software/systemd/man/latest/
- https://tadeubento.com/2023/systemd-hidden-gems-for-a-better-linux/
Systemd does a lot of stuff I guess it is easier to just lean based on what comes up / you need. There isn't a single path.