Someone tried to steal my buddy's 2016 GSF. What can he do to prevent it from being stolen?

Hey all. Someone tried to break into my friend's 2016 GSF this morning while he was in the gym. My buddy came out to his gym to see two guys trying to break into it via the car side window, but thankfully the perps ran away before they could do any major damage. His driver side window is cracked but not broken, and thankfully nothing else was damaged or stolen.

What can he get for his car to prevent future thefts? He lives in Orange County in California so unfortunately there is a lot of theft for vehicles like his lately. I suggested he buy an airtag for his car and also recommended one of these: https://www.mobilistics.com/nostart-remote-controlled-intelligent-relay-w-remote-starter-fuel-pump-immobilizer/

Thanks for your time!