Breakfast sandwiches are an AWESOME take along breakfast. Portable and nutrient dense. They'll keep for a while, too. I've eaten them after they've been sitting out forever just because I forgot/didn't have the time to eat them prior.
Grapefruits are totally portable. Bananas are good because they're more nutrient dense than other fruits.
Muffins are always delicious too. Banana, carrot, zuchinni, whatever, full of nuts and deliciousness. His favourite is cream cheese stuffed carrot. Sounds laborous, but it's not.
I used to take a bunch of oats/quinoa/millet/bulger/whatever with dried fruits, coconut, nuts and milk. If you use oats or bulger you can let the raw grains and add ins soak overnight in the liquid & they'll be ready to take out of the fridge in the morning. Otherwise, clearly, you need to cook quinoa/millet/rice. I packed them in small pyrex containers so I could grab them whenever. Anyway, grain cereal is delicious.
Likewise, pilafs + veggies + protein (meat/nuts/beans) are perfect. I love pressed or baked tofu and walnuts in mine, especially with yam. Mmm.
Speaking of yam, baked yam stuffed with almond butter is mindblowing.
I love tofu. I can eat it pressed with salt or previously cooked/baked in a sandwich or pita. I have never had a problem with tofu outside of its package not keeping well for a while. I don't know if your husband is crunchy like that (mine is not), but I think it's delicious!
My husband loooves his sausage (smoked sausages like Landjager). They're perfect snacks for him because they're nutrient dense and keep at room temperature. He also loves the cheese/cracker (or bread) combo along side. I send cheeses/cheese curds that serve at room temp. He keeps this stash of food at his desk, no fridge.
Peanutbutter/banana/date/sesameseed/sunflowerseed pitas are also delicious and keep forevah. Falafel keeps too. We always take those types of sandwiches backpacking/roadtripping/errand running marathons. Super light, keep forever.
OH! PEANUTS in shell. DH could eat pounds.
Did I mention my husband is a beanpole & I make a concerted effort to stuff him full of nutritious calories?

We're pretty busy people, portable food is the best!
I'm all hungry now!

: