Sorry to hear about your injury....
I had a similarly devastating injury five years ago. index finger left hand, severed nerve and tendon, two surgeries to repair. Obviously couldn’t play bass right away - it took me a year to get back in the saddle and do a gig on bass. I also play guitar and that wasn’t possible either. I mostly focused on playing what I could physically play: pedal steel guitar, lap steel and dobro. I had never played these before (beyond a bit of slide guitar). And I got pretty good at it. But a year after the injury I was back gigging regularly on bass.
Interestingly, When i retired from my long term gigging band last year (on bass), I was picked up almost immediately to play pedal steel in another band!
Finger is still far from perfect. I’ve got mobility and sensory issues making fine motor skill tasks a bit difficult. Playing bass is no problem since I’m not bending fingers much. Playing guitar still presents some difficulty for some chords and lead bits, but I can get by.
Oh, and for post surgery recovery I was in a cast and bandage rig for a while and then I saw an occupational therapist for a few months - showed me how to get most of my motion back. Severed nerves take time to reconnect and get sensation back- something like 1mm per month. I let my massage therapist work on the scar tissue as well. She showed me how to work on that tissue and maintain some flexibility. Five years later and I still do the stretching and massage routine.
