I don’t recall ever needing the --user option, if the command is ran by the user.
if you were running the command via sudo, then yes, you would want the --user option.
Understand that flatpaks can be installed system wide, or on a per user basis.
if you are not careful you can install the same flatpak system wide when you just wanted it installed by the one user.
I wasted a lot of disk space and time before I learned how flatpak works.
the OLED deck has the feature from what I can tell to wake in Bluetooth.
my older LCD deck, does not seem to have the feature.