This is an older discussion with good info about sick days/stomach bugs.
In addition to the video linked in the discussion, here’s a link to a slide deck Dr Ponder used for a parents’ webinar several years ago. A couple of slides have good lists of foods/liquids to use during illnesses.
I don’t have links readily available to info on carb absorption during a stomach bug, but my daughter has had more than I can count over the past 10 years. We can see carb absorption affected not only during & after the illness, but also the day or 2 before onset of symptoms. Usually, she needs less insulin overall for 2-3 weeks after the bug. It’s fairly common, at least with kids.