To do a streaming without using internet I think jitsi could work [1],
but it is centralized
As a decentralized solution, check out [2]
Maybe you already know, but Ring/Jami does not work
without Internet
unless you manually configure a local bootstrap.
https://git.jami.net/savoirfairelinux/ring-project/issues/581
good to know!
[1]
https://gitlab.com/guifi-exo/wiki/blob/master/howto/jitsi-meet.md
[2]
http://peerstreamer.org/