Two quick and easy ones for our very picky eaters are tortilla wraps with a protein and salad /broccoli slaw mix (just buy precut slaw).
1) Sautee ground beef or turkey or whatever (add chopped onion if you have time). Then top with whatever easy condiments of choice. Lately been into Japanese bbq sauce which isn't at all spicy (this one -
https://bachans.com/products/the-original-japanese-barbecue-sauce) and squeeze it on when almost done cooking and a little extra over the meat in the wrap. Throw into tortilla with a salad/slaw/whatever mixture and serve.
2) Black beans seasoned with olive oil, honey, lime juice, cumin, garlic powder, salt and pepper. No cooking necessary. Top with crumbled queso/cojita/whatever cheese and some salad/slaw/whatever mixture and serve. Cilantro if you're being fancy.
For whatever reason, my kids will eat some proteins better if hidden in a wrap and buried under other things. Whatever works.