For your unit files, you have Wants in the [Install] section. That is not correct. Wants belong in the [Unit] section. The [Install] section is where you define WantedBys. You may want to read the man page for systemd.unit.
To interact with user services, you do have to always use systemctl --user.
If you put your user unit files in /etc/systemd/user, they're accessible to all users. If a particular user wants to enable the service, they can run systemctl --user enable $service. Defining the unit in ~/.config/systemd will mean only the one user will be able to start the service. Defining the unit in /etc/systemd/system indicates it is not a user service but a system service.