Yes, Nokia 8 does have OIS.
No. Technically, Nokia 8 is not a 100% water-resistant but it has got IP54 certification. That means that the phone can withstand minor water splashes.
Yes, you can use 2 4G Sim cards in this phone.
No. Nokia 8 does not have face scanner.
It’s safe to say that if a smartphone like this had shipped from the Nokia stable a few years ago, the Finnish company might never have had to step back from the mobile business.