I haven’t seen any mustang grapes this year. Lots of vines but not grapes. IIRC, July 4th was the time to pick them. I’ve made mustang grape jelly but have be careful because they break my hands out and talk about burrrrrrrrn!
It will soon be time for pickly pear jelly, too.
I know about mustang grapes burning when you get too much juice on your hands. Hadn’t thought about prickly pear jelly or wine. I remember a fellow years ago who used them for wine. There are plenty in our area.