[jjd-uk]

Note also that once any changes are done to allow DV from mvk containers, the number of devices this will allow to playback DV will probably be a relatively small number of Android devices, as there will still be a requirement for the device to have been official certified by Dolby.

Assuming that the device is Dolby Vision certified, once the changes are made, would mkv DV playback work in CoreELEC as well or only in Android?

As far as I'm aware the necessary bits are baked into the hardware, so might be possible if the device ships with Android and DV is listed as supported but it's possible to dual boot to CE. Where DV will be impossible to get out is on Windows or any x86 Linux variant since as far as I'm aware there's no certified hardware.