Gentoo has a little list¹, along with suggestions for modifications. Instead of modifying the programs, one could experiment with a shim library and leave the program code unmodified to see if that's a viable path towards portability. The end benefit would be portability to systems lacking systemd proper.
(Now, the importance of portability is a separate question. If you want systemd to "eat the world" it's even a negative value.)
This kills me when, of course all these apps were already portable for decades and only just recently all now need a "viable path towards portability".
(Now, the importance of portability is a separate question. If you want systemd to "eat the world" it's even a negative value.)
1: https://wiki.gentoo.org/wiki/Hard_dependencies_on_systemd