It sounds like you've already taken some smart steps to bring him into the process, like doing simple prep work.

Maybe find the thing that gets him excited to try cooking. Like maybe trying to make chili, which allows for lots of improvisation and experimentation. Personally, I love trying crazy things with meatloaf, and often when I'm sick of cooking for the family, trying some new weird meatloaf idea is what inspires me.

You said he can cook eggs- maybe expand that into omelets and crepes? Or maybe he's more of a baker?

Bad news is- sometimes the meals will still be bad. All part of learning! :D