What is he eating for lunch, op? You could judt enourage him to eat those same foods at breakfast. Also, cereal (like kashi berry fruitful) with soy or coconut milk is a fast decent protein breakfast.

Ezekiel English muffins with nut butter, tofu scrambles, avocado, walnut or cashew milk, pesto (minus the parm)

I'd just cook hearty vegan meals for dinner and eat the leftovers for breakfast. Lots of options in Indian & Asian cuisines. Even Mexican/ Latin.
I'm not a huge fan of traditional American "breakfast foods" and the vegan versions of things like muffins, pancakes etc that I've tasted so far haven't been inspiring.

burritos!

and I hope he is helping with all this or that you decided planning and making vegan breakfasts would be your Lenten sacrifice!

Beans and rice - you can make these sweet (add maple syrup/cinnamon) or savory

Arroz con leche - just use non-dairy milk... Rice, non-dairy milk, vegan butter, cinnamon, hemp seeds for protein (or nuts if you can do that)

Sweet potato with vegan butter, sprinkled with hemp seeds

Muffins! So easy and you can add in a ton of hemp/flax/chia or whatever other kind of seeds - you can make them as caloric as you need. Off the top of my head - banana oatmeal or apple carrot are favorites... Cookie + Kate is a website that has great recipes.

Smoothies
Cereal with almond milk
Chia pudding with fruit
Pancakes
Pb&J
Bagel and peanut butter
Muffins

Legumes, quinoa, dried fruit

Hummus

Is he allergic to nuts or a family member? If it’s not him let him eat nuts when he’s out of the house. They’re a good source of healthy fats and protein for vegans.

Gardein brand has a lot of vegan breakfast foods. They have a vegan breakfast sausage, breakfast patties etc. you get them in freezer section at regular grocery store.

Can he eat seeds? Oatmeal made with plant based milk with fruit and sunflower seeds.

Also, remember that he doesn’t have to eat traditional breakfast type food for breakfast. Batch cook things like lentils (we like yellow daal which is stupid easy) and rice, and plant based ground beef style crumbles with taco seasoning over rice. Both are hearty, and have a good mix of protein and carbs.

I also like to heat up Hodo marinated tofu (available at Giant and Whole Foods) and serve with steamed veggies like broccoli which is really quick in the morning. I eat a lot of edamame too.

Any suggestions?

My kid decided he wanted to go vegan for lent. We compromised on vegan until dinner time, and then normal dinner. He's in his adolescent growth spurt, and plays three sports. He eats like a horse.

So, besides a ton of avocados, what do vegans eat when they want a lot of calories.

Oh, and we're nut free due to allergies.