Léonie - main character in the Georgette Heyer novel 'These Old Shades' - was the name I decided to use for my future DD when I was only 19 - but when I began my family ten years later I only had sons!
I have only met one in my life. People called her Lee, which I didn't like. Leo is nicer as a nn.
Love it, I know two, one Leoni, one Leonie (both pronounced Lee-oh-nee). One gets Leo, one Noni. Leo is cute for nn, it's quite common for 'boys' names to be used for girls; Sydney, Dylan, etc. Go for it.