Zapstream is advising to use OBS
it spits out a single stream, that can be split into multiple via restream.
Restream is a paid service and it therefore requires kyc and is not needed.
OBS is open source and has plugins that would allow to stream to multiple platforms without restream
https://obsproject.com/download#linux
Plugin
https://github.com/sorayuki/obs-multi-rtmp/releases/