omg, that would be such a nice feature if someday implemented...
Literally one post above yours I linked a working current build with the feature implemented 
EDIT: In case I misunderstood you and you were actually just asking for this feature being included in the official LibreELEC builds, I 100% agree.
As I posted elsewhere, my solution to this problem, with 8.2.0 LibreELEC dual audio build:
Display MoreWorking 8.2.0 build (not mine, just happy with it):
Forum post at kodi.tv: [Project] Dual Audio Output support (Krypton/Jarvis/Isengard/Helix/Gotham/Frodo)
Direct Dropbox download: LibreELEC-Generic.x86_64-8.2.0.tar?dl=1
The manual pulseaudio setup (from mraction's post #15) also kinda works for me, but this is easier
In case anyone wants a pulseaudio setup for Intel NUC 6CAYH:
/storage/.config/autostart.sh:
Bash#!/bin/sh pactl load-module module-alsa-sink device=hw:0,0 pactl load-module module-alsa-sink device=hw:0,3 pactl load-module module-combine-sink sink_name=combined slaves=1,2Also not sure if needed, but it definitely won't hurt to make the file executable: chmod +x /storage/.config/autostart.sh
Working 8.2.0 build (not mine, just happy with it):
Forum post at kodi.tv: [Project] Dual Audio Output support (Krypton/Jarvis/Isengard/Helix/Gotham/Frodo)
Direct Dropbox download: LibreELEC-Generic.x86_64-8.2.0.tar?dl=1
The manual pulseaudio setup (from mraction's post #15) also kinda works for me, but this is easier In case anyone wants a pulseaudio setup for Intel NUC 6CAYH:
/storage/.config/autostart.sh:
#!/bin/sh
pactl load-module module-alsa-sink device=hw:0,0
pactl load-module module-alsa-sink device=hw:0,3
pactl load-module module-combine-sink sink_name=combined slaves=1,2Also not sure if needed, but it definitely won't hurt to make the file executable: chmod +x /storage/.config/autostart.sh