I've run the Pivos Xios XS software on my GREF18 board, so maybe this will work the other way around:
[8.0.2] LibreELEC 8.0 builds for MX2/G18
It has not been tested, and bricking is of course your own responsibility.
Topicstarter KOPRajs has said to try to make a release for 9.0 if certain bugs concerning sound have been fixed.