I posted this over on the HRT board but forgot to post it here: Musicians, at any point in your transition, have the changes affected your playing because your hands shrank, lips changed, you maybe added dexterity and small muscle control from becoming more of a woman??
The bone structure in the fingers won't change, neither will their length. If you have lip augmentation / plumping that will change your ability to play instruments. IF you have any kind of surgery in the jaw, you risk numbness and thus increased difficulty controlling the embouchure. If you're a professional musician, don't count on HRT helping you overall. That being said, psychosomatic (placebo) effects can still help. If you think it helps you , it can help you
If you have osteopenia/porosis, that will diminish the overall structure of the bone, but that's going to affect your hips, back, etc long before it has a noticeable impact on your fingers. You might break them more frequently which will certainly hamper your musical performances.