This was a nice surprise. It looks simple but it does the job. It allows me to put my pics and videos on my private cloud. My pdf also and search is fun. It allows me to create markdown docs too. A simple docker install and you have your private cloud. Top! It is not NextCloud. Nor it pretends to be. I like it, might keep this running and maybe put it to work. Thanks.

Is there a simple list of features, and their completeness/ maturity?

I've not dug, but on first look https://opencloud.eu/en is a vague brochure with no real information.

it would be nice to include a feature comparison chart between nextcloud and opencloud

Was this done because the performance of Nextcloud is poor? I have been using Nextcloud for a few years on my own (admittedly overkill) hardware and haven't had performance issues, but I am the only user.