As I'm now less 'afraid' of testing other boxes' builds on my Minix X8-H Plus, I've just installed the M8S Plus build of @surkovalex of May 28th, found in this folder: Index of /image/devel
This build works quite well. Wi-Fi and Bluetooth still don't work, but the video is better for the following two reasons:
1) It is for the first time, that I've been able to hardware decode h265 content on my Minix X8-H Plus. Great news, so it IS possible!
2) It is for the first time, that I've been able to have my Minix output full-screen 4K video on my Sony TV from Krypton! Only in 24Hz but that's a hardware limitation.
Like in the builds of balbes150 the audio output is good too, with passthrough working except HD passthrough. But also that seems to be a hardware limitation.