Here's a previous Noa thread.
I love it, for many reasons. The simplicity, the sound, the meaning in Hebrew (movement, uprising, revolution), and the echo of a lot of lost short Hebrew-via-Yiddish names like Bluma, Brenna, Gila, Yona, etc. that I wouldn't use in the UK now. I don't see it like Gia, Lia, Mia, Tia, etc - which are all traditional short forms for various names - nothing wrong with them but Noa is its own name.
You did mention that you don't want a popular name, so I'd think about the popularity of Noah - even though it is not the same name it sounds the same, and you might find "boy Noah, girl Noah" as annoying as, say, Olivia A and Olivia B.
I'd still use it.
Others that might appeal in some similar ways (apologies for repeats):
Cara
Hope
Lea(h)
Nadia
Nava
Noora
Oona
Rue
Sela
Zillah
Zoia