This is a great suggestion.

I think it would be really helpful if one could link to some docs or some comment explaining this possible behavior of systemd a little bit further. Having such link in the PR (or IMO in the commit message) makes it much easier to later understand why that config was added (esp. in case that behavior of systemd needs to change in the future).

You mentioned another "NUT" service where this setting is already required. (I assume "NUT" stands for "Network UPS Tools".) Here in nixpkgs (at current master) I only found one service which also has Before=final.target set, which is apcupsd, did you mean that one?

The explaining link there from the OpenSUSE forum sadly seems broken (& archive.org is down too at time of writing …). I assume this post was migrated to this location, but that does also not explain why/if final.target is required.
The commit 95e2006 introducing that line is also missing further explanation.

Re: NUT, I was thinking of #344940.

I think it would be really helpful if one could link to some docs or some comment explaining this possible behavior of systemd a little bit further. Having such link in the PR (or IMO in the commit message) makes it much easier to later understand why that config was added (esp. in case that behavior of systemd needs to change in the future).

Good idea, but the only place I remember that talk about this is man systemd.special, and it doesn't really go into enough details (or I haven't found them).

I'm also the author of the apcupsd.nix module, but that was like 10 years ago. I guess I did the same trial and error testing and came to the conclusion that before = [ "final.target" ] was a good thing to have back then too :-)