My husband needs easy, healthy food for work

https://youtu.be/M5fJF2GF0H0
Try this recipe.most easy , healthy and tasty Sandwich recipe

I second Phil's approach. Satisfying and lots of protein sounds like the way to go. I'd add:
1) dredge chicken pieces (I like thighs) in a combination of melted butter and Dijon mustard, then dredge in panko crumbs, then bake. This is good cold or at room temp, either whole or cut up in a bowl meal or in a salad.
2) grill chicken, make a homemade Caesar type dressing, and put both along with shredded romaine inside a crusty bread roll/mini loag
3) grill steak, let cool, slice thinly and put inside a crusty bread rollwith lots of sauteed mushrooms and some garlic viniagrette.
#s 2 and 3 can be made ahead, wrapped up tight and kept in the refrigerator under a weight, and then sliced off in servings for a couple of days.

the Guy works in a steel mill , he needs protein
1) Prebaked sweet potato with chopped tomatoes, crunchy roasted chickpeas, parsley , some nuts, red onion, olive oil , salt pepper and smoked paprika , all he has to do is reheat for 30 seconds.
2) Thin sliced steak as sandwich or over a salad.
3) cheese plate , with salami and ham , his favorite cheeses and jams with crackers or bread ,
4) cold shrimp ( if he has a cooler) tossed with oil lemon garlic
5) tricolor bow-tie pasta salad with cubed salami or ham , mozzarella, oil & balsamic vinegar.
6) smoked salmon on an everything bagel
7) poached salmon filet over salad
8) nicoise salad
9) chef salad
10) toasted baguette with ricotta cheese and roasted sliced carrots
11) toasted bread with smashed avocado and roasted spiced chickpeas.

+1 to Happygoin's idea of a grain salad! I really love wheat berries, which are high in protein, nutty in flavor, and chewy in texture. You could toss those with some roasted veggies, toasted nuts, crumbled hard cheese (like cheddar), and a simple oil-vinegar dressing. Also love Stephanie B's idea of a cold noodle salad, yum.

Some format suggestions...use insulated containers (Thermos or others) to carry hot stews and soups, cold smoothies, salads, fruit.
Also, for nutritional value, there are savory smoothie recipes.

My first thought was Farro Salad with a simple olive oil, vinegar and mustard dressing. It’s healthy, filling and doesn’t need refrigeration if you curate your veggies carefully. Grated carrot, green onions, broccoli, cauliflower, fennel, celery as an example, along with walnuts, almonds, pecans or pine nuts. Crumbled blue cheese or feta would be alright without refrigeration for a few hours (I’ve eaten it on airplanes) and didn’t suffer. The possibilities are endless.

I make a big batch of Farro on Sunday night and dress it while it’s warm. It absorbs the dressing better, I’ve found. Then your lunches are half done for the week.