I would advise to use the other arm, according to some studies you can slow down muscle loss by up to 80% in your injured arm by training the other one.
You can focus mainly on abs, neck, possibly grip and legs but I would defenitely train the good arm and shoulder with dumbells.
If nothing else this will give you time experiment and try out every single excercise possible (even if it seems stupid or really unorthodox) could be a lot of fun!
One arm deadlifts and snatches come to mind as well.
Also there is a world record holder in raw powrtlifting who squats without even touching the bar with his hands, if you place the bar low enough maybe this can work for you.
Don't know more possibilities but I would see this as a chance to experiment with crazy stuff and be back at the gym as soon as I feel like it, not when some untrained doctor that can't even Squat what I press overhead tells me to. They really don! They know everytjing and evety person is different so they CAN'T know the time you should stay out of the gym.
Come to think of it one arm snatches might be tough since you cannot use the other hand for support.