as Geralt he has his skills right? Why not become a mercenary then? If he introduces advanced technology, everyone is going to want to kill him and take his inventions, it's just painting a target in the back.
Google translate
He could move storage for Nobles later on because with inventory he would be the best mover with best security.
Maybe when he goes to westeros and wants to make money.
Idk how it would be incorporated but it's just an idea.
Jayus is a simple man with simple dreams, no need to corrupt him. MC should move forward without him, unless he actually wants to stay in Qohor. Then again I would actually want to know what MCs aim is