There is a genetic dwarf variety called Cheyenne that I researched because I was in your position of not wanting a huge tree.
Two problems:
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You’ll still need another variety to pollinate it, and that variety won’t be a genetic dwarf. (Though I suppose you could graft a pollinator to an existing tree? Theoretically? But I’ve heard grafting pecans is a pain in the butt.)
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It is disease prone enough that it is not recommended for planting in the SE. (Where I live.)
Here’s a link from the UGA website: http://pecanbreeding.uga.edu/cultivars/cheyenne/cheyenne.html