No. Nokia 8 does not have an IRIS scanner.
Yes, Nokia 8 does have a hybrid sim slot. You can use either 2 sim cards or 1 sim card & 1 MicroSD card.
Yes, Nokia 8 does have an OTG support as well.
Yes, you can record 4K videos on Nokia 8.
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.