Serious guitar player and coder. There is some overlap, but the areas prone to RSI are slightly different. I code 6-12 hours a day and play guitar 2-6 hours a day, most days in the middle of both ranges. Posture and form are really important in both but I've never had a problem where I couldn't do one or the other. However, I do notice some discomfort if I get sloppy or lazy doing either.

In guitar, posture, a good drum throne (roc-soc high stool with the back) and a more ergonomic guitar (Strandberg Boden) has allowed me to play as long as I'd want to daily as opposed to slouched over in a chair or on a couch with a Les Paul (that shape further exaggerated my slouch).

Similarly, good posture, an aeron chair, a good bright monitor with a monitor arm and a splitboard (UHK) has saved me from the aches and pains. My prior setup had me seriously wondering if I needed to start seeing a specialist for occasional numbness in one of my hands.

There's definitely some overlap, but overall it's fine. Definitely a good mental break. The guitar is a fingertip and wrist and forearm thing. So the wrist overlaps a bit but it doesn't mind me. I also am deliberately very aware of my arm and hand pain and tiredness.

I also play electric guitar so it's easier to play generally.