I used to experience this things from couple hours session on my pc.

I started to rely more on my keyboard which helped with right hand wrist pain ( vim for the win )

I then got a good chair, that when I need to type I have it sit upright so my back is cokpletely straight, and when I take my controller to play a game for longer sessions ( dead cells ) I can tilt it back a little, keeping my back straight and still keep a good posture that doesn’t hurt even after 5 hours ( not purelly 5 hours of just sitting and playing )

What helped me the most tho was getting one of those wrist training things and a pair of dumbells to train the parts ofy body that eould usually feel stiff after a longer session.