Scapular winging: strengthening exercise

So yeah, you probably know I had a bad shoulder accident. Things are getting better. One thing still not ok is strength around the scapular on one side: there's winging, it's a bit too far away from the spine and when lifting up the arm the shoulder still rolls a bit to the front. And that reduces strength in that arm. I have the feeling I've done what I can with physio. Using exercise bands just doesn't add more there.

Any idea how to build more strength there? Have exercise mat, some kettlebells, bench with barbel and dumbbell sticks and weights, bands, and a pullup bar stuck in a door frame that is both too narrow and probably too weak for this. Can't drill into walls and ceiling, and tree protection order in place, thus not a chance outside either.