If your looking to do some soft tissue work on the lateral delt a simple lacrosse ball against the wall and rolling out the meaty bit of your side delts will do the trick, doesn’t have to be to fancy. Also check out 2:39 in this video if you want to get a good banded mob than can hit that general area:

Does it feel like its the soft tissue limiting your range of motion overhead, or more in the joint itself? I think all these banded shoulder mobilizations found in this video done with some consistency should help you out.