Thanks chewitt, finally I got back to my locally compiled 8.0 that had no problems downloading and installing Docker. It looks like I can't use official builds anyway, because they lack the bmc2835-v4l2.ko kernel driver, and I need it to create devices of type /dev/video. I use Docker to mjpg-stream a USB camera connected to a Zoneminder server while Libreelec is running. Save for some video freezing here and there when playing HD media, it can go for days without a hitch. Still amazed of what you can do with LE and Docker even in such a limited device!
Thank you!