NDI Input and output should be implamated according to this post
NDI Backport
but that is as far as I can see for dev build 2.3.xxx (I think there was something for the 2.1 NRK too)
In that version you are in config-file not taking about “ivga” but “NDI”.
iVGA is a older format from Newtek, and according to Newtek they havent produced anything using iVGA for many years now, so they wont support it anymore.
I would also switch to CasparCG 2.3.X as soon as there would be any form of “Beta 1” release.