I have one of these two. it may feel as hard as bone, but it is technically movable (don't try -- instant bad nerve pain)
If you can, try getting into plank position or just lean your body weight on your hand, like against a wall or something, as you bend your wrist to support the weight. If that makes your wrist hurt on the back (knuckle) side of your hand, that's indicative of a likely ganglion cyst.
Here's a really good study on it (which should CALM your fears!
):
https://pubmed.ncbi.nlm.nih.gov/29085728/
Basically, nobody with this has cancer or anything. Just a bad wrist.
Good luck best wishes