So, I encountered this other post from a year ago about the installation problem. And added what I could find happening on my system to help somebody fix it. It seems for me that there is a Docker or kernel problem on Yunohost (for Raspberry Pi 3).
Also, there is apparently this how to in French. Also people encountered the installation error there. But I cannot distill if they found a solution and what it is.
In short: Could anybody please help? This issue has been around for long and current documentation surrounding the Collabora installation are definitely not enough to get it installed. I would be very grateful if you could get the installation working. Please let me know if I can do anything or you need more information. I tried everything I could find, but I am out of my depth now.
UPDATE:
@ljf I read your post again… am I correct to assume that the Collabora in the gui store is not working and your testing thing is? I would be so happy if Collabora (and perhaps onlyoffice) became available for anyone to install through the store again 