I’m just going through this; had the collar bone plated 9 weeks ago today and although the bone itself is beginning to feel quite good (after 3 months of non-union the surgeon was worried about “waking up” the healing process) there is still soft tissue discomfort at the AC and sternum ends and I have a frozen shoulder, which the same surgeon says he will fix with a small cuff operation.
I did 30 minutes on the turbo yesterday using Zwift to try to make it more interesting. I’m quite impressed with Zwift because it motivates you better than just staring at a blank wall. I got a smart trainer for £300 “ex demo” from my LBS and rigged it up with an unwanted laptop and a TV screen, which works seamlessly.
Are you doing strengthening exercises on the arm? My physio gave me a yellow latex band, which I’m finding very good attached to a door handle.