At 370 pounds, I tried chair yoga. I could only do the arm stuff; my legs were too big to do any of the lower body stuff. Don't be discouraged if you are the same. The upper body stuff helps. I couldn't comfortable sit on a folding chair.
I was thinking of finding tai chi online, but haven't done so yet. I figure I can just do what I can with it.
IF you could get to a pool, that would be great, especially if you could get it as physical therapy.
Another thing I do is lay on my side in bed and do leg lifts; started with 2 and worked up from there.