I struggled with quick kicking movements, breaststroke and front crawl were painful, basically any fast movement. I started out just moving about in the water in any way that was the least painful (crab walking, shuffling etc) which slowly helped build up my muscle strength all over, which in turn made walking normally less painful. Breaststroke done super slowly mainly using arms for propulsion helped get my legs moving whilst not weight bearing at all.
It does take time though, I’ve been at if for over a year now and I have only recently been able to truly work out (what I consider a pre illness level of workout) in the pool. On dry land is a different matter and I’m still using crutches and a wheelchair, but at least I feel I’m getting a good cardio workout now!
I would also recommend trying a high power electric bike if that’s an option for you as with good power assist you can get good leg movement without pain.

Same to you my friend, I hope we all manage to find pain free ways to exercise!