I'm not a big fan of nicknames-as-given-names but there are a few that I find more "acceptable" than others.
I like:
Maisie - Prefer as a nn for
Margaret or
Mairead, but I don't mind it as a given name
Mamie - nn for
Mary or
Miriam Millie/Milly - nn for
Millicent,
AmeliaTillie/Tilly - nn for
Matilda Tess - actually I prefer this as a given name (not as fond of
Theresa for some reason)
Libby - nn for
Elizabeth Nellie/Nell - nn for
Eleanor,
Penelope Sadie - ok on its own
Annie - ok on its own but prefer as a nn for
AnnaMaggie/Meg - nn for
Margaret (or
Marguerite)
Lulu - nn for
Louise,
Louisa,
Tallulah Lottie - nn for
Charlotte