Yeah a Arm collabora container would be brilliant.
I can not give you definites as its all a little hazy from Collabora, but by users.
I found this which is actually the reverse of what we need.
https://sedden.github.io/blog/2016/04/11/automated-builds-for-arm-docker-containers-on-intel-hosts/
But it is the reverse and so do we only need qemu-x86-static and the reverse is true?
The Resin.io forums have a lot of community info on raspbian containers.
https://forums.resin.io/c/projects
https://hub.docker.com/r/ioft/armhf-ubuntu/
https://hub.docker.com/r/forumi0721alpinearmhf/alpine-armhf-nginx/