Everything else i've figured out about other shoulders really isn't helping here. I'm going to rig and pose this after this step is done
1 Answer
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Cut a hole in your cylinder (maybe use less vertices by the way):
Extrude inwards and right click > LoopTools > Circle (you need to enable the LoopTools addon):
Extrude on the axis:
Bevel if the transition is supposed to be smooth: