@Brown19 from an educational perspective
the command pm2 info MagicMirror
would have shown you what program. or script was being launched
and then, when you open a terminal window, the .profile and .bashrc scripts are run to setup the user environment.
the .bashrc has the venv command in it
when pm2 launches a pgm at startup, it is not using a terminal window, so those script are NOT run
you can also use the source command to load them at any time
so you could have done
source .bashrc
instead of
venv…