Hi,
Please try hardware encoder nvv4l2h264enc. Some samples for reference:
Stream processed video with OpenCV on Jetson TX2 - #5 by DaneLLL
OpenvCV, Gstreamer, Python camera capture/access and streaming to RTP
And can set insert-sps-pps=1 idrinterval=15 for a try like:
Gstreamer TCPserversink 2-3 seconds latency - #5 by DaneLLL