Get a Shield or something of the sort and stream from that.
Or
Stop paying for 4k if you don’t want to run Windows/OSX/use smart TV apps/get another device just for that, you’re wasting your money.
Edit: Lol at the downvote, streaming services don’t let you see 4k content from a browser, that’s just a fact, so unless you are ready to use a platform that allows you to watch 4k content then you’re wasting money by paying for it. None of them have a native Linux app either, so your choice is Windows, OSX, TV app or Android based device.