When I read about working together with collabora I liked it. Then I read that I need to integrate it by myself, then I realized that this would be complicated and is not suitable for inexperienced users.
So they will still go for commercial cloud hosters since there is no out of the box solution with serious online office for them.
My request is to integrate collabora by default or add is as an optional app.
However I am unsure, whether this is technically possible.
This is already possible. There is a app for Collabora Online Integration, and a docker image, you should run on a separate server.
Announcement: https://nextcloud.com/nextcloud-and-collabora-bring-online-office-to-everybody/
More Information / Setup Instructions: https://nextcloud.com/collaboraonline/
I meant a standalone app/integration without the need of setting up a backend server. Is this technically possible?
Collabora Online is an very advanced piece of software and nothing you can run by doing one click in the frontend. This is caused by the LibreOffice Online Server which must run in the background. Unfortunatly, I have to say no from this side.
But there is something going on at the Nextcloud VM, developed by @enoch85 and @ezraholm50 
Maybe it will be integrated there in the future, which would make deploying Collabora Online for endusers very easy.
Alright, already thought that. I am using Nextcloud at a hoster who offers it out of the box, so I have no option to install something on the backend, thus the request. The VM approach sounds nice, though.
You just need to setup the Collabora Online Stuff on a seperate server via the docker image … There is no need to take any advanced options at your Nextcloud Server You just install the connector there - type in the adress of the previous setted-up Collabora Online Server - and then - everything should work fine.
Follow the official guide under:
https://nextcloud.com/collaboraonline
Ok, good to know. Currently I don’t have a separate server though. If I had one, I’d probably run Nextcloud from there as well 
We are indeed working on a simple script thats ran with 1 command. It asks for some information like your site url with a nice whiptail/input box.
That should install the docker and setup a vhost. The first tryout should be ready in about a week from now. Same thing goes for Spreed-Webrtc.
Collabora: https://gist.github.com/ezraholm50/01e3b1a3b33f329b081e1ed6c632d3ea
SpreedMe: https://gist.github.com/ezraholm50/cecf009f5576428507cbdd92a050c9b7
Testing is appreciated (Make sure you do it on a VM and not a production system.
@clel Don’t count on it. Another option is indeed to set it up on another server.
Thank goodness. I’ve spent around 50 hours trying to get this configured to work so far. Installing the Spreed server proved remarkably easy, but configuring it to work with my Nextcloud instance has proved hair tearingly hard.
Got it to work yet? If not I can help.