It is impossible for Inter Milan to sell Lautaro Martínez. He is the best striker in Inter Milan, they will keep him as long as possible. Moreover, he still has 3 years contract duration in Inter Milan, it expires in 2026. So, there is no reason for Lautaro Martínez to leave Inter Milan now. He also shouldn't be interested in moving to Saudi Pro League, it is not a top league in the world. Even if Lautaro Martínez has the intention to leave, he must prefer to move to La Liga or EPL. Real Madrid and Barcelona must be interested in him, the top clubs in EPL also want to sign him if he has an issue to leave Inter. But so far, I don't hear any issue that Lautaro Martínez really wants to leave.
You are right, somehow Inter Milan want to let him go while Martínez is the only reliable player in the team I don't think Inter will take that option unless they don't want to continue competing in all leagues. We know Inter Milan is having financial problems but they can still overcome it by bringing in loan players or release other players who are not too important, after all Inter Milan have already made enough money for the release of Andre Onana at least so far they've earned 108 million after letting a few players go and spending 27 million on signing new players that should be more than enough to pay players this season.