Is /usr/etc something that could be a thing Fedora wide? The way
rpm-ostree does it, it's making a copy of /etc and does a three way
merge so you get updated config file defaults. But without that logic
available, is it bonkers to consider applications learning to look to
look first in /etc, and if the config isn't found there to go look in
/usr/etc?
A lot of packages have been following the systemd module wherein they
check for /etc first and if it's empty they will use the version in
/usr/lib[64]/<default_config_path>, but this is being done on an
app-by-app basis. I think the OSTree solution is actually quite
elegant, since it doesn't require every application to change its
config file handling.