[asavah]

Would it be possible to implement this?

https://github.com/EHfive/pulseaudio-modules-bt

Possible yes, but I personally think it is unlikely as this will result in a non-standard PulseAudio installation which will results in problems with upstream PulseAudio support.

The pulseaudio-modules-bt maintainer should be sending improvements upstream to the PulseAudio repository - the following discussion is relevant and suggests there are several problems:

https://github.com/EHfive/pulseaudio-mod...t/issues/1
https://github.com/EHfive/pulseaudio-mod.../issues/61

If you still think adding this package is a good idea then please open a feature request on the LibreELEC forum and maybe someone will be interested in taking it further - PRs welcome etc.  

I've been using EHfive/pulseaudio-modules-bt for a while now (even contributed a crash fix), so far I've had no issues at all after crash on startup issue was fixed.
Apt-x works very nicely
IMO it's worth the time invested into adding it.