Bicycling and water jogging are both great but the former is far more accessible. Flat pedals are better if you’re injured/recovering since you can adjust your foot positioning (if clipless aren’t dialed in right you’re kinda locked in and can exacerbate injury, and if you don’t unclip in time you fall over). Padded gloves to keep vibration from aggravating things. I was in a boot for 6 months from a gnarly stress fracture but my doc cleared me for biking and I basically lived on a bike.

Also range of motion, biking helps for that since you’re constantly articulating your ankles and loosening up the ‘rust’. Trace the alphabet with your toes a couple times a day to stay on the up and up.

Check with doc ofc, and might help to get bloodwork so see if you’re deficient in anything and also see if there’s some root cause if you’re injury prone. Turns out I had a vitamin D deficiency so I started taking a ton of D+K2, couple years later I got back into running and building up mileage pretty realistically and went couch to 50k in 8 months, before that I was always getting injured. Not saying it’s specifically that, could be lots of things or nothing, but in my case I found that thing out and the sky was the limit afterwords. It’d be cool if it was some overlooked thing like that for you