u/Direct-Cat420

For context, I’m 20 years old and a male who has been lifting since 15 with a focus to just grow in size and build muscle. Recently I wanted to start building some bodyweight strength and realized that I am lacking in mobility. At 220 lbs I have struggles with touching a bar to my chest either in pull-ups or just trying to stretch. I’m aware that this could be a shoulder mobility issue and I have resistance bands to try and do some rotational exercises to try and improve my mobility and strengthen muscles I otherwise haven’t used. Any recommendations for exercises or protocols to help me regain my mobility?