All the manufacturers claim their boxes can stream 4, 6, or 8K.
However, I know from others that's not always the case. One Android box claims 4K but in fact the maximum resolution is 720P even when watching on an actual 4K tv. This has been verified with YT and a PC where the same video as 720P on the box claiming 4K but 2160P on a PC.
4K is supposed to be 2160P at 60 fps from my understanding.
The specs below appear to show the maximum specs at 1080p (not 2160P) or am I misreading the specs:
H.265/HEVC Main/Main 10 profile@level 5.1 high-tier
H.264/AVC BP/MP/HP@level 5.1, H264/AVC MVC
VP6/VP8/VP9/ MPEG1/MPEG2/MPEG4/
Support 4Kx2K decoding 1080p@60fps/ 2x1080p@30fps/ 4x720p@30fps simultaneous encoding
Which manufacturer claims 6k/8k? Nearly all android boxes are "just" 4k capable, mainly because 70% of the boxes out there are based on the same SoC's.
No, 4k is just the resolution and since 99% of current sources are 24/29 Hz, 4k@30hz will still work. In most cases you want the player to switch to the actual video framerate anyways, since that will avoid playback hiccup's.
What you mean it clearly states "Support 4Kx2K decoding", the 1080p modes just clarify that it can decode those at higher 60fps, so i would assume 4k/30hz. Not sure what the "encoding" is about, since no android box is actually good at encoding. So without knowing what actual model you are talking about, the "encoding" statement makes little sense.
What could be more important, depending on your TV or future plans is what HDR standard is supported. If you don't have a Samsung TV, than you want HDR10 and Dolby Vision support if possible.