Hm. I like
Celestine. It's a little too frilly for me to use IRL just because of the "tine" part though.
I think
Tenney is good as a nn.
I like
Marion (but prefer
Marian if it's a girl),
Joanie (as a nn for
Joan), and maybe
John. I like
Jan is it's YAHN on a boy, but I'm not big on it if it's JANN on a girl.