Similar, 133" projector setup and surround, also 77" 4k oled in the living room… so I wouldn’t watch typical movies on a hmd, but there are some exceptions…
3D movies are great in a HMD, also watching stuff when away such as on holiday/traveling can be good too (thinking of more recent portable hmd’s of course).
75hz won’t be a problem, there is a 60hz mode too which is better suited with watching movies. For almost all, the frame rate is a lot lower than that anyway.
A 2080 will be fine too, watching stuff in big screen or virtual desktop or whatever viewer of choice is generally lower resource-intensive, you can go even further to use non 3d environments too if needed but I doubt it will be.
An 8KX will look ‘a lot’ nicer than Rift,quest(1),vive overall, especially the lack of sde is more important in my opinion… the fov however isnt as important, you typically don’t fill that much of your viewing area with a movie screen, so it’s more the environment feel such as a cinema that is the immersive part the fov can contribute towards.
Overall in my opinion a quest 2, reverb g2 and 8kx are all viable and decent enough for watching movies (not taking into account audio differences), so I would judge your decision on any other factors and use cases you might think to have.