Can usenet be used for free?
Some universities also offer free news servers for their students.
The free servers usually don't offer bin/audio/video groups, at least I don't know any.
What is Kbin’s identity?
If I remember correctly @ernest once described kbin as a "gateway for the fediverse" (but at the moment I don't have a source for that).
This would allow kbin to gather and integrate even more services from the fediverse - maybe