This isn’t an app, but I really like Bloglates workouts. She has a great workout plan and videos to go along with each day on YouTube. Her Instagram @bloglates also has good resources and is a super positive space. This is what I have been doing lately and I love it!
I like to study and copy exercises from YouTube. I use Calisthenics movement to learn and correct my posture and Thenx to copy the moves