In some cases, unit files are present in testing packages (that moved me to create https://bugs.gentoo.org/show_bug.cgi?id=unit-in-stable with the packages I hit), most unit files available in systemd-love overlay were recently committed (https://bugs.gentoo.org/show_bug.cgi?id=systemd-love), but there are more pending unit files blocking https://bugs.gentoo.org/show_bug.cgi?id=448882)
You can try to find unit files in other distributions like opensuse, fedora, Arch, Mageia and try to make them work on Gentoo. In that case would be nice if you could report the bug and make it block bug 448882
fixing summary to match the long history of our release tracker bugs :)
Pending bugs are not blocking stabilization if they don't block the stabilization bug directly
Job is done and 3.8 has been replaced by 3.10 as stable. Closing.