For food, my kid has has had varied strategies, with varied success... But one we like a lot when there is a split second turn around is squeezable fruit pouches, they go down quick and easy and are gentle on the tummy.
But as a mom, with a neurodivergent kid with learning issues, I get the struggle with homework! We always try to be upfront and let the teachers know exactly how little time we have in between activities, but there were times when it was a real struggle. Grades 9 & 10 were the worst because she wasn't allowed a spare in which she could do homework so she took a few classes that were less likely to require a heavy load like dance, choir, and drama. Now that she's finished all of her required credits for graduation, she's only taking a couple of classes for her own interest so that gives her the downtime she needs to work on homework. Our policy has always been to be proactive though, it is usually easier to work with the teacher before you run into issues with late assignments or poor performance. Good luck!