Takes a few minutes to heat raw oats with milk to make porridge. Add some fruit and you've ticked a lot of the boxes for a proportion of a day's required nutrients as indicated by USDA and similar authorities elsewhere. I've hardly touched a commercial cereal for years and have no regrets.

Raw Oats? https://reedir.arsnet.usda.gov/codesearchwebapp/(S(z2xdbujdr...