Hi Hermann,
You're welcome, looking forward to hearing some feedback from you.
Regarding the matrix integration, or any other for that matter, gosl code was written with extensibility in mind.
Meaning, all the helper code required to create a new connector is packaged and easily reusable.
If you take a look at telegram and msteams connectors, you'll see they're ~90% boilerplate code with a few lines of system specific api calls.
That makes the complexity of implementation depend solely on the API of the other system and implementers familiarity with it.
Guessing the time estimate is not simple, depends on a lot of factors.
For me, never having used the matrix and reading its documentation for the first time now, it would be much more than for someone familiar with it.
Together with the test system setup, understanding of the protocol, libraries, code, figuring out the preferred workflow, testing, etc.. I'd guess a couple of weeks (with my usual load).
For someone intimately familiar with matrix, probably it's measured in days.
I'd suggest you open an issue on github with this as a feature request, and if you have the resources to start working on the connector yourself, we'll be more than happy to assist you getting around,
or else we'll see if could manage the time on our side to tackle this if there is wider interest for this integration.
best,
Petar