I have some music which is multi channel Flac with Auro Native encoding added. This format is fairly common with the hifi multichannel classical labels such as 2L. The last 2 or 3 generations of Marantz/Denon AVR, Arcam/JBL Synth, some Yamahas, most recent Onkyo/Pioneers and many other brands support this format. On the source side no special support is needed except the multichannel PCM output must be bit perfect otherwise it will not detect the Auro Native encoding on the AVR (The encoding is actually stored in 4-6 bits of the 24bit PCM).
Using the same hardware if I use Windows then it works as long as the output is WASAPI and volume is set to 100. Ubuntu 24.04 works as long as I disable Pipewire and use Alsa. Libreelec however does not seem to output bit perfect PCM as I cannot get the format to detect. I'm not sure if this is some sort of config issue or a bug. I can provide sample files if someone with a suitable receiver wants to test.