Since Nextcloud Talk was not even usable with 3 participants in my case, I decided to try and implement a backend based on NodeJS which should be compatible to Nextcloud Talk. As the SFU I currently focus on Janus (since I believe Nextcloud is using it too) but it should be possible to write connectors to others as well.
I seem to be on a good track and the first prototype mostly works, but it is still work in progress as it is difficult to guess the right responses from the backend. You can find the source and track the progress here:
Any help is very appreciated!
This is not finished and still not working very well. It is supposed to be a proof-of-concept and not (yet) stable enough to be used in production environments!