8K is great for stills. In fact, one of the main reasons for 8K displays is that panels are made for televisions, computers, and digital signage in more or less the same process. Computers and digital signage will clearly benefit from 8K, televisions are sort of along for the ride.
A long time ago, televisions were driving resolution, and the new (at the time) 1080p standard caused much nerd rage for effectively rolling back/stalling PC display resolutions for a decade (obligatory XKCD: https://xkcd.com/732/). I’m glad we’re past those days. But for movies, at even large display sizes, the benefit of 8K is dubious. That said, 8KTVs often have a lot of the newest tech that makes them very nice displays regardless, so you’re not going to be disappointed.