The creator of this software streams on twitch, using the "linux" tag which I follow around. I think she uses debian stable or unstable last time I was on the stream. She also has an owncast, which is like an open source self hosted twitch.
https://expiredpopsicle.com/about.html
I really enjoy when people dogfood software.
It's mostly a self hosted thing I think.
Also, it's more of a "meta service", as it's a package thay contains many relevant other services, like opencloud (nextcloud/gdrive alternative), element/matrix and more. It's designed to be the whole package.
You can also consider deploying or paying for SAAS versioms of each software individually, which may be better because, as you've noticed, the docs for some of the German software is all in German.
Also, it does seem to have a SAAS:
From the faq.