Sorry to hear of your injury and hope it isn't impacting daily life too much!
I've broken a few bones in my time on Earth (including my collarbone) and for me the key is to remember the physiology of healing, and not get frustrated and do stuff which would make recovery slower. It's normally 6-8 weeks for bones to knit back together, and perhaps a couple more months to get back to full strength*.
There are lots of great bass skills to learn without picking up an instrument. Stuff like rhythm, ear training, active listening and various aspects of theory could keep you busy for a couple of months (or a lifetime!). It's likely there's materials on your learning platform for all of this.
Don't stress about forgetting what you've already learned. You may feel rusty after a few weeks away from the instrument, but it'll soon come back!
*I'm not a medical professional... seek a professional opinion.