I like it, but it reminds me a little too much of Bolonia (Spain) which brings to mind bologna. So I think I'd prefer Apolinia, Apolena, or Apolline.Pola wouldn't be my choice of NN, but it works fine.
I think Apollonia and Apolonia are very sweet. I like Pola and think it's a great nickname that could work for any age. Though, personally, I'd call an Apollonia 'Polly' while she's young.