I have used the sweetened condensed milk boiled in the can many times for pies. I believe they used to be a restraunt in Tn named Charlie or Old Charlies that served it.
I always used a premade chocolate crust. Put 2 cans of the sweet milk into a large pot and cover well with boiling water very low boil for 2 hours and keep adding water to keep the cans covered. Remove and let them cool well before opening. Smooth into crust, refrigerate and when cold serve with whipped cream. The milk turns carmel color.
Very good & very sweet.