@tomberry, First congratulations on your recovery from Covid...a large feat in itself!!

What you describe from weakened legs and leaning forward is something my sister encountered following a serious surgery and lengthy recovery. At first she had trouble taking even a few steps and feared falling over if she stood for even very short periods.

Initially, she was too weak for pt and her doc suggested she lie flat on her back and just practice lifting & bending her legs. He also suggested she use a walker for increasing her sense of balance and stability. While the walker did give her support, stability and confidence and allowed her to walk & stand for longer periods, it did not address the "leaning forward" you mention.

Now there are adjustable height walkers that make a great difference in allowing the user to stand straight and look forward rather than down. Also utube exercises are available to help increase core and leg strength for those of us elders who don't need p.t. but do need to build strength. Hope you get back to your more active life style quickly and wishing you the best.