Any way to block Safe Mode on a Macbook w/ an M1 chip?

My teen son is highly addicted to porn. After tons of research, I have set up very strong DNS filtering and powerful website and app blockers on his computer. These launch on login and are are unable to be killed because Activity Monitor and other workarounds are blocked. I have admin rights, he is a standard user. However, he's figured out how to start the Mac in Safe Mode, which doesn't launch the website and app blockers on startup and thus are rendered useless. My son has a Macbook Air with an M1 chip. And yes, we're working on other methods to get him to stop. He has no phone, for example. As we work through parenting - is there a way to disable or block Safe Mode from being used?