Posted this here but thought I’d provide some feedback to this forum as well.
Using a Droix X3 and the build 9.2-funhouse_2006.7-Generic I have now had a successful boot into CoreELEC using device tree sm1_s905x3_4g.dtb but with the caveats listed below.
Booting both sm1_s905x3_2g_1gbit.dtb abd sm1_s905x3_4g_1gbit.dtb both just present a black screen with no activity on the boot media.
From the bootable build of CoreELEC I was able to test the following using an LG C9 OLED and Onkyo reveiver and media on a USB drive.
Working - 4K60 HDR remux
Working - 4K24 HDR remux
Working -1080p60 remux
Working -1080p24 remux
Working - Dolby Atmos / TrueHD passthrough
Working - DTS-X / DTS-HMA passthrough
Not working - LAN
Not working - WiFi
Not working - Bluetooth
Not working - Playback of content (HDR or SDR) would quite often either start as a black screen or end as black screen. You could still hear the sound so restarting and/or ending the media playback would show the screen again after an attempt or two.
Not working - Dolby Vision passthrough brings up the HDR option on the TV whereas when the content is played back directly from the USB port of the TV it comes up as Dolby Vison.
Not working - Suspend puts the device to sleep but there is no way of bringing it back afterwards as no inputs seem to work.
The performance of the menu interface and playback was excellent though which gives me some hope for the device.