Please can you describe the movement she has available with her hands while waiting for the op?

If using a tablet is an option there are lots of apps which provide low- impact drawing options, Procreate is popular. Some tablets, including recent ipads, are compatible with a Bluetooth mouse - a track pad, rollerball or small joystick could be an option if she's limited to finger movement rather than whole hand/ wrist. Similarly to use illustration/ photo editing software on a laptop or pc.

There may also be practical art media & processes she can still access too, moving away from traditional drawing, painting & sculpting. Installation, collage, modern pointellism, cynotype, photomontage for example can all be less reliant on fine motor control/ use of the dominant hand.