Hi !!!
Where I live
Valentina is very common.
Everyone goes with NN
Val or
Vale (va-leh) or
Tina.
Odette is beautiful and I would not use a NN.
Allegra is hard to give a NN..
Allie or
Ali or Aly could be fine even if I dislike them a lot. I would go with the full name. Maybe
Greta could be a short form. I dislike it anyway. I prefer
Allegra as its own.
Odessa could be Odee/Ody or Dessa.
Byeeeeee