[Bajann]

Yours I would consider an Edge use case scenario - not many Android users at all would go to that much trouble and expense of UHD HDR Bluray manipulation, let alone even using HDR for anything but test clips.

I agree for anything HDR you need to use the Android OS.

But even that has issues with no Auto Resolution switching for top quality 1080p > 4K video upscaling - that is better done by a 4K TV - not a media player if you want superior quality. Its a PITA manually switch Android Resolutions for the majority of normal Kodi 4K users.
AMLogic Hardware produces "Soft" quality 1080p > 4K upscaling picture outputs, same complaints as nVIDIA Shield owners report.

Everyone is different - for me Android Kodi is a no goer - deinterlacing is to badly broken with Kodi Krypton AND I cannot stand 3:2 pulldown judder with 23.976fps video playback when AMLogic Android Kodi dynamic refresh switching does not work on some platforms.

Best solution is an easy Dual boot setup - you don't compromise too much with either OS then.

I don't feel I'm compromising much, and have been happy with Android. I'm definitely an edge case, but nearly everything I'm buying now is UHD HDR...just got Planet Earth II, La La Land, and now Logan (with the HDR Noir edition pack) is just around the corner . I've finally gotten to a spot where there are no distinguishable changes between the internal player PQ, UHD bluray player PQ, and kodi android PQ when dealing with this type of media. I agree about the pulldown, but I've been able to get refresh switching working in SPMC on all my media on a few different (up to date) android firmwares.

I don't have any interlaced material, and have disabled deinterlacing globally using the sysfs interface which has improved the PQ on some file formats it was still trying to deinterlace (amlogic bug).

I'm comfortable flashing new firmware using the amlogic usb tool because I have a few devices which make testing quick and painless. Is there any firmware you can recommend for Krypton automatic refresh switching? I'd just recently tried the minix firmware because I'd seen posts like yours which claim the refresh rate switching works for Krypton's mediacodec implementation.

Edit: BTW, those libreelec issues aren't only true for HDR material since with hevc, 10 bit encoding is more efficient.

Edit2: Replying to @wrxtasy 's edit: I meant "mini m8sII," but I've tested minix based firmware . Also, I'm an idiot...I had to reboot to get refresh rate switching working in Krypton after modifying those playback options. So I tested another box with an android TV based 6.0 firmware, and was also able to get it working in Krypton after modifying those settings and rebooting. There should definitely be a notice in that settings menu that a reboot is required...but not surprising given china.

tl;dr: I flashed multiple roms (including modifying my own) just because I was too dense to reboot after modifying a setting.

Edit3: if anyone's in the same position I am (doubtful), you need to disable hdmi self-adaptation, enable in refresh rate switching in kodi, and then reboot for the self-adaptation change to take effect.

Thank you for your help.

Can you send me link to that rom (minix based)?