Thanks a million for your hard work jernej, and everyone involved in this project !
Using your images on OPi PC and OPi PC+, they work great.
On PC+, I managed to install the image on the emmc of PC+ simply by doing dd if=libreelec.img of=/dev/mmcblk2, no other steps were necessary.
I used the image posted by someone in the comments which contains a fix for the wifi (thanks to the poster). I'm wondering how to keep the board updated and not lose the wifi fix. Any ideas ?