I would use Vivi as a nn for
Vivian and pronounce it vih-vee. As far as
Viivi goes, I don't know Finnish so I'm not sure.
I think sometimes when we start liking a name we notice it more, and feel like we see it more often even though really it was always there. I haven't noticed a big increase in the number of
Vivian appearances. I do feel like I see a couple of
MY favorites a lot more than I used to though!