I love Oona/Una!! For you I would maybe lean a little more towards the [name_f]Una[/name_f] spelling but I think its a gorgeous name.
There is something a tad unusual about Oona. I think we’re unused to Double O, with one being the capital. Perhaps the “icky” is the likeness to “goo” or something.
I’ve come around to Oona after NB, but I had the same reaction your friends and family had when I first started seeing it around. At the end of the day, this is your child, not theirs. And they have the responsibility to be respectful and polite regarding your choices.
If your partner isn’t sure, however, then I’d keep it in mind and keep looking. Otherwise it wouldn’t be fair on them.