FWIW, openrc (or any other init) does not eliminate the need
for systemd - all standard parabola openrc systems include parts
of systemd; becuase there are many programs which will not run
otherwise - openrc can even be configured to use systemd as it's
init

parts of systemd are effectively core system libraries now,
required by essential programs, for example via 'device-mapper' alone:

'cryptsetup' 'grub' 'lvm2'

to "get rid of any-and-all-things systemd", you would need to
maintain a system without 'systemd', 'notsystemd', or 'elogind' (eg: by
replacing 'elogind' with something else which provides 'systemd',
'systemd-libs', and 'libsystemd')

That would be too optimistic, utopian even. ;) I should have worded it differently, as I realize there are packages which provide a systemd-like layer for compatibility. What I meant was simply that “systemd-run” does not belong on a non-systemd system.

E.g, that the line above in:

/usr/lib/udev/rules.d/69-dm-lvm.rules

Is changed from–

ENV{LVM_VG_NAME_COMPLETE}=="?*", RUN+="/usr/bin/systemd-run -r --no-block --property DefaultDependencies=no --unit lvm-activate-$env{LVM_VG_NAME_COMPLETE} /usr/bin/lvm vgchange -aay --nohints $env{LVM_VG_NAME_COMPLETE}" 

to–

ENV{LVM_VG_NAME_COMPLETE}=="?*", RUN+="/usr/bin/lvm vgchange -aay --nohints $env{LVM_VG_NAME_COMPLETE}" 

or something similar so that LVM volumes activate.

The reason for routing this via systemd is apparently in the event there are hundreds of LVs to set active, as that will take “a couple of seconds” (which apparently is too long in the systemd-world...)

# When the VG is complete it can be activated, so
# vgchange -aay <vgname> is run.  It is run via
# systemd since it can take longer to run than
# udev wants to block when processing rules.
# (if there are hundreds of LVs to activate,
# the vgchange can take many seconds.)

btw.–I am not sure if the abovementioned suggestion is the “correct” way to do this, as there is also an “IMPORT{program}” notation being used in the (Red Hat-provided) script, in addition to the “RUN+=” notation which runs vgchange via systemd-run.