I think you can get egg free pasta, something like that or rice can be used as a good carb to go with things like bolognese, mild chilli / curry etc. Would he eat potatoes if you did a casserole, as they would be a very different texture? I think personally I'd be looking for ways to hide veg into his meals (have recently learnt that this is what my mum use to do for me) as I was very fussy although no allergies
That is a hard one. Maybe chicken gougon-y things, with some sort of dip like houmous or sweet chili? What about crabsticks? (I hate them but DSS, 7, loves them). If he likes tuna mayo could you try something similar with tinned salmon? Maybe Chinese rice noodles with bits of chopped up meat, cashews, soy sauce and whatever chopped up veg he will eat?