I don't really get this one
From my understanding, Luna marries Newt Scammander's grandson (I could be wrong) and Ginny marries Harry Potter.

Furthermore, I don't really feel as if they have any scenes that would indicate to their relationship being of the romantic nature.

However, no disrespect to you if you ship it and I know, probably, that at least one "Linny" shipper will see/read this so I'm sorry.

Score out of ten:
5/10 because I'm neutral

Probability:
1/15
0/10