As I have found no viable solution for non-admins, I created a small python script to export a single channel including all files: https://gist.github.com/RobertKrajewski/5847ce49333062ea4be1a08f2913288c

I'd like to save conversations as a file to see that
a) as a last level backup
b) as a opportunity to keep conversations that I love
c) to reuse content.
A procedure like https://faq.whatsapp.com/de/android/23756533/ would do the trick for me.

You can use our API to export any posts that you want. That would let you build a script/application that does exactly what you want. Ideally, it would authenticate against both our API and your KM system's API, and move the specified post over automatically.

Here's a link to our API docs: https://api.mattermost.com/#tag/posts%2Fpaths%2F~1posts~1%7Bpost_id%7D%2Fget

And to answer your other question, im not sure if this is something supported by other chat systems - this is the first time ive asked. Im asking in here because my colleagues have started to use this application and really like it.
Im trying to find the balance of real-time, quick and easy collaboration with capturing the knowledge output from these interactions. Helping to turn tacit knowledge into reusable explicit knowledge. Essentially stop people having to ask and answer the same thing over and over again, by saving it, making it searchable and browsable through KM.

Linking and copy and paste are options. We are talking about support interactions so the fewer clicks and applications the better to adopt the right behavior (saving the knowledge).
With the enterprise option, does it have to be the entire database? Could we not have a pick and choose option? Im guessing this would an API thing that is out of my scope.
I was looking for a shorter term option (exporting) before a potential longer term option (some kind of integration).
There may always have to be a copy and paste element so may be exporting is not the right term for me to be using.
Anyway any ideas here much appreciated.

You could still post the link to the MM conversation in the KM system and accomplish the same thing. Alternatively, you could take a screen shot, but that isn't very search friendly, or copy and paste the interaction out to the KM system.

We do support exporting data out of Mattermost, but it's an enterprise feature, and exports the entire database, as it's intended for big companies that need to archive messages for legal compliance reasons - it's not really made to export individual conversations, so it's probably overkill.

Is this something that is supported by other chat systems? What sort of export format would you want to see in this case?

Thanks Jonathan. It is an option, but i may want the source of truth to be outside of mattermost, and i would therefore prefer to link out than in, if that makes sense.

Take this engagement we are currently in for example. If it happened in a mattermost channel, i would export it to our other knowledge management (KM) system, and then if someone else asked the same/similar question, i would link them out to where ive saved this interaction.

I want it to be collaboration and KM rather than collaboration vs. KM.

Does posting the permalink to the conversation satisfy your use case? Just hover your mouse over the first post in the thread, hit the elipses menu, select Permalink, and copy+paste that to whatever channel that you want to share the conversation in.

Note that if the conversation took place in a DM or private channel, people clicking on it who weren't a member of the conversation won't be able to see the conversation.