Been poking around for a while for an easy way for one of my clients to stream from his iPhone to multiple sources at the same time. Mostly to YouTube and Facebook simultaneously.
Well recently FB relaxed their stringent “Only Stream Here” requirement and now you can indeed stream live to both YT and FB at the same time naively.
The first app (that I know of) to do this is Prism Live Studio - free in the app store. Version 2.2.0 was just released yesterday and has a TON of features you will want to check out - if not for you, perhaps for your clients.
Log into FB, log into YT and select the channel, page or group you want the stream to go to.
There is also a desktop version which is a simplification of OBS.