Run preset-all of user units on first boot?

[Nils Kattenbeck <nilskemail@xxxxxxxxx>]

Hello,
I know that preset-all is run by the manager at startup if it is the
first boot. However, this does not seem to be run for user units (i.e.
systemctl --global preset-all).
Based on my findings the presetting is run very early and hooking in a
new service file with WantedBy/Before does not seem possible (and
would also require a daemon-reload).
Is there any other method of how to preset these files at boot? Is
this not done on purpose or has the need for this never come up?

Thanks for the help.
Greetings, Nils