In the context of a TV Streaming Box, the decoder itself is basically the only large factor… and as the site you provided shows, the nokia box supports h.265 4k@75hz, and 4k@30hz h.264. VP6/7 seem to be unlisted, so I can’t tell if that’s a mistake, or would be deferred to the CPU for decode. This ends up leaving the question which services are you wanting to stream, and which encoder are they using?

The CPU/GPU only need to be fast enough to smoothly run the UI, and other possible decompression tasks that aren’t h.264/h.265.