It would have to be. Xylitol and Stevia are two of the safest zero cal sweetners out there. Another good thing to sweeten with is star anise seeds. Be careful though. They are strong. You can easily over power something with them. I made some almond flour matzeh and used three of them to sweeten them. It was WAY too strong. I hardly could eat it.
Yes, if it is assuredly non gmo. it is safe to be derived from corn. Xylitol can come from many plants. It is a natural sugar alcohol produced by the plant