@Pengggwn perhaps I should have said significantly increase mental load?
Most of what you described there isn't mental load, it's physical time.
It is mental load to think "I must get lunch bits" or "has she picked up her lunch?".
But it's not mental load to empty it, make it, shop for it.
If you don't make packed lunches then the initial thought of it might seem like a lot. But it really isn't.
If you are food shopping for your family anyway, how does it increase mental load to add a cucumber and a carrot to that shop?
I didn't post to tell the OP to just do it, I shared what I hope was helpful advice - to use foods that are long life, ones you use anyway in your house, don't stress about variety.
It's all about automation.
I make a packed lunch every school day. There is ZERO mental load in making sure my child has it with them, because it's automatic. It's the same amount of mental load to think "has she got her school bag" - not more. It just becomes routine.
Ditto having food. It is not an extra 20 minutes of thinking every Saturday. It's just part of my normal shopping.
How much time do I spend thinking about lunches? It really is negligible.
I think people are too quick to shout "mental load!" because it's the latest buzz phrase. That said, it's genuine and it's helpful in some cases - especially in a relationship where it isn't balanced!
But I'm a single parent making a packed lunch every day, and I promise you that the additional mental load really is negligible.
As for getting up 7 minutes earlier... do it the night before and combine it with other activities. I often do it whilst listening to spellings, or just chatting about the school day. It really is not that big a deal.