I was in a similar situation with silvery wallpaper I ended up painting the walls very pale grey- just grey enough so that white photo frames etc. look nice on it. I have bright sunshine yellow with it to make it warmer- and thinking of adding bits of turquoise and magenta as well to make it a bit more cheery :)

I'd go with blue, white or silver gray.

Your house looks fab and the hallway seems to be spacious - you lucky thing!! I think dark blue could work well - my own hallway is white but with one wall painted dark blue - and I love it. However I’ve got serious house envy (and specifically hall envy) at the moment of a blogger who I also follow on instagram - your hallway made me think of hers because the height of your picture rail is similar to the height of some panelling that she’s added. She’s used lovely pale muted shades, and I think it’s gorgeous. https://malmoandmoss.com/home-1/2019/12/6/03ehb3k5ckvleip5u7tunnvgqnoc3o

Gorgeous sofa. There are many shades that will sit nicely. I love the dirty pinks like Dulux Blush Pink or F&B Setting Plaster. If you want something more neutral try Skimming Stone or Dulux Egyptian Cotton. Something bolder is navy, looks lovely with green sofa.