I donno man, obviously we've gone over this ground with my son rather intensely as you might imagine with a grade school kid wanting to go out like/with his friends.
If its a VERY small town yes you might be screwed but his dining choices have been stuff like:
Steak dinner with all the fixings hold the garlic bread.
"grilled meats" on a salad (grilled chicken ceasar salad no croutons is pretty stereotypical)
"lets hit the salad bar"
As for "basically can't do fast food"
Grilled stuff is not breaded. Screwed on fish fry friday night. On the other hand the local BBQ joint will serve him anything, just not on bread. Cajun stuff on rice is good.
Look for low/no carb option even if not heavily advertised/promoted they'll probably do it anyway, just like they'll serve you a chocolate shake even if its never been in a TV ad... Culvers etc will toss a slice of meat on a bed of shredded lettuce. One thing to look out for is some places will fry their french fries in the same oil as they cook wheat stuff, while others will not, while others will tell you its safe but he gets sick anyway.
Yeah taco bell and KFC you're pretty much SOL. On the other hand other than the rolls he does pretty well with almost everything at boston market. Pasta houses like olive garden yeah you're pretty much SOL there too. OTOH the local non-chain non-corporate genuine italian family restaurant has started serving fresh GF pizzas and they taste good.
We've gone to a couple buffet type places and chunks of meat and fish and salads and fruits tend to be pretty good.
If its not breaded, not pasta, and not on a bun you're Probably good plus or minus fillers, flavorings, and contamination.
"So it's a huge social handicap."
Yeah on the no beer thing. In a decade when my son can drink he's going to have to be a rum -n- coke guy like his old man.
"can't eat most desserts"
"Fruit, the original dessert" Bananas Foster aka flambe bananas Ice cream in a dish not a cone. Strawberries and cream Chocolate dipped anything. Chocolate dipped everything. Sherbets and ices and all manner of frozen and gelled creations. I am well over the drinking age so this may or may not apply, also I'm an old married guy so I don't give a F what people see me drinking, so I'll admit I like a little glass of sweet fruit wine for desert or one of those icy "girlie" booze drinks for dessert. If you don't like the taste of a well made grasshopper or a fine sweet cherry wine there's obviously something wrong with you, and I don't need to care if only girls are supposed to drink that stuff. If I made chicken cooked in wine sauce or whatever the leftovers get sipped for dessert.
The stuff you can't eat is cakes, pies, cookies, ice cream cones and not much else.
Look on the bright side, my son is allergic to milk too, so exclude dairy then you're really in for it at dessert time.