Being in a ketotic state should protect against hypoglycemia and hypoxia. I believe dom d’agostino has done some work on this topic.
I doubt you’ll find much research pairing water fasting with semaglutide as fasting in and of itself isn’t studied that much.
If you’re unable to get much info anecdotally, I would just tread carefully. Get some glucose syrup based candy like haribo goldbears and just keep them handy in case you start feeling off.
Been on ozempic, I didn’t have any trouble with hypoglycemia. My doctor even told me it’s a rather rare side effect in general.
I did finger picks with a glucometer and I only showed low once but felt great