I always try to consult the man pages for these kind of questions (you can search by typing ‘/’ in the man page). Here’s what the systemctl manual has to say in the specifications for the --force option:

Note that when --force is specified twice the selected operation is executed by systemctl itself, and the system manager is not contacted. This means the command should succeed even when the system manager has crashed.

No, it’s a side effect of how everything’s handled by rpm-ostree currently, and it’s on the list of issues to be fixed.

See Here for more info

/etc is writable, so no reboots are required. That said, /etc is treated in a special way and each deployment will have its own /etc, based on the previous one.

So if you make changes to /etc then revert to a previous deployment, your changes will be reverted as well. But if you make changes and upgrade (or do whatever to create a new deployment), your changes will bu preserved.

Looks like you’re on Fedora Silverblue (or other Atomic version). This is happening because the system groups are in /usr/lib/group rather than /etc/group and this causes the issue you’re seeing here. You can work around it by getting into a root shell with something like

sudo -i

and then getting the group added to /etc/group with

grep -E '^dialout' /usr/lib/group >> /etc/group

after that, you’ll be able to add your user to the group with

usermod -aG dialout pipe