I learned to shoot with pinch grip. We didn't just use thumb and forefinger, there were most of the time two fingers under the arrow pulling the string as well. Depended on the weight of the bow. I can still pull 45+ with it no issue. If I can get up tomorrow I'll try to get a pic of how it was done.
Pop was raised by survivors of the Seminole Wars. I learned from full blooded Seminoles, and this is what the ones in my family did (before they switched to compounds.) I'm the last holdout for trad in the family, but most of the rest are passed on or dealing with injury. Being from a mining family, that's not too uncommon.
I still shoot with it sometimes. It helps me compensate for ruining the last two fingers on my right hand. I've been shooting with it more now that I've not got any thumb rings. I should make up some new arrows and get out there since we're quarantined here.