That is so weird. Having grown up in a very mixed Italian, Irish and Portuguese almost 100% Catholic neighborhood, I thought I had seen every type of religious statue. When we were growing up, almost half of the front yards boasted some type of mini shrine - usually the Virgin Mary classic garden statue with arms extended, white dress with blue shawl - occasionally a different pose holding baby Jesus. I have never seen a Mary statue posed sitting - even in the manger scene she is always kneeling never sitting like Buddha.
I live in a still solidly Italian Catholic neighborhood. In Italian Catholicism Mary ranks above Jesus. Acceptance into the neighborhood pretty much requires a Mary statue somewhere in the yard. The classic pose is:
View attachment 146959
as you noted arms extended palms up and a slight bend in the right knee. Most commonly the pedestal is a globe of the earth and Mary is standing barefoot crushing the head of a snake. When I'm out walking with my wife and we pass one I recite, "Hail Mary full of grace kill the snake and step on it's face." At which point she hits me and says, "ssshusss! someone is going to hear you!" I have never before seen Mary sitting down as in the antique mall photo.
Joe