If feeling sick, I stick to light foods a piece of toast or a cracker, but in the main I’ve found that when I’m unwell BG normally raise, so keeping them down is more problematic than worrying about a hypos
I did several years ago suffer the Norvak virus, which left me vomiting for 14 hours and not even being able to keep any fluids down and several weeks to recover from it fully.
I used the sick day rule as I was on basal/bolus regime, so inject my normal background insulin, injected insulin following these rules, checked my BG every hour… Sipped water boiled water I could manage… When I was over the worst, I used boiled water didn’t eat anything for 30 hours or so… But when I did it was a bowl of vegetable soup…