we will be driving from florence to venice on a sunday and wanted to stop at a winery, looking for suggestions.
Be aware DUI laws are more stringent in Italy than in most of the US
Sorry, I cannot address your specific question.
It is difficult to just stop in. Most require appointments and in my experience, very few are open on Sunday. You may be able to locate wineries by using Google Maps and zeroing in on your route. Then see if they have websites and details about hours.