Hi,
The first thing you should check is if the simplest RTSP test case works or not.
Try this:
$ gst-launch-1.0 rtspsrc location=RTSP_URL ! rtph264depay ! queue ! h264parse ! nvv4l2decoder ! nvvideoconvert ! "video/x-raw(memory:NVMM),format=RGBA" ! nvegltransform ! nveglglessink sync=False