Installing packages on the host system via `rpm-ostree` is _insanely_
slow, especially on Raspberry Pi devices. The main reason I chose to go
that route for managing the SSH host certificates was to avoid having to
maintain the systemd units in multiple places. I think the trade-off is
worth it, though; bringing up a new Raspberry Pi is significantly
faster, by 15+ minutes, if we do not have to wait for `rpm-ostree` at
all.
Dustin