I don't think exercise is ever wasted, but having a baseline fitness is probably important if you are working towards visible results--if you had to consistently modify/lessen the workouts, you probably weren't able to work towards the visual you want. COVID obviously makes this harder, but consider joining a group exercise glass or something that works on total body strength.

I think seeing results (could be moving from a 3lb to 5 lb dumbell!) is important for the mental part of fitness and would help prepare you to take on this or any program with more success. I think walk/running intervals (maybe one minute running, two minutes walking) can help build a little more lower body strength help with cardio. Also maybe doing consistent exercises like planks can be helpful--maybe start at 20 seconds every day and work up from there ,or take some exercises you like and try to do them each day, and each week up the rep count. Switching things up is important for you body, but repetition can help you build up those basic muscles. Of course you should talk to your doctor and and exercise professional, but I've found things like this help me a bit, so that's just my two cents!