@OCX:
I don’t recall having an issue with doing any of that without Wowza. My only issue when using the built in solution was specific to IP cams as they use a non-standard format of RTSP. I have tested the Kaltura CE RTMP with OBS and had no issue loading the streams on any device through my Kaltura CE player. You can always ask more specific questions and @jess or one of the other users will reply as soon as they have a free moment.
My suggestion is if you have a development enable the functionally and test it out to see if it meets your needs. You can run both parallel (e.g. Wowza and NGINX on same server) but you have to change the RTMP ports on one of them so they don’t not create a port conflict.