Our house went through a phase like this. DS one turned veggie, DS2, autistic, had ARFID and would only eat a very limited range of things. DH and I wanted healthy foods with good flavour.
In the end, I tried to do dinners that worked for everyone eg
Pasta 'pomodoro' (though actually I added loads of other veg too, very finely chopped, so DS2 would eat it. DH and I could add olives, chillies, fresh herbs, capers, anchovies. DC could add grated cheddar.
Wraps. Roast a chicken, buy salad and some of those pouches of spicy tomatoey beans if you don;t feel like cooking a sauce. Some have spicy bean wraps, others have chicken and salad or all three.
Simple veggie risotto (peas, shallots or leeks, very finely diced carrot and celery or ready made sofritta) with shredded chicken leftover from previous day for people who want meat. Salad or broccoli on the side for those who want it.
Sausage or burgers and chips. Vegan sausages/burger for the vegan. Real ones for everyone else. Beans, peas, and/or steamed veg and salad on the side.
Mezze: humous, baba ganush, whipped feta or other dips, salads and flatbreads. If fussy DS just wants grated cheddar melted on his flatbread with some carrot sticks and iceberg, that's fine.
Avocado pasta - mashed avocados with lemon juice and zest, sundried tomatoes, fried garlic, pine nuts or cashews and chilli flakes. You can add the ingredients individually at table so people choose what they want. If they hate it all, they get a jar of pasta sauce they can heat up in the microwave, with grated cheese.
Baked potatoes with baked beans, grated cheese, tuna mayo, salad - people choose what they want. If they hate baked potatoes, they get the same fillings with a bagel.
Roast dinner. Put a small nut roast in the oven for the vegan and the rest is the same for everyone.