I use my own custom image (hand-made, not automated, and X11) and i build everything on the board.
I think you are looking for this: (Introduction to rockchip-multimedia ppa for ubuntu jammy - #18 by amazingfate)
It’s Wayland but i think you can have X11 as well.
Looks like Wayland is 3x faster for video accel. but not stable as X11.
About the latency, i think there is a parameter/property to suppress latency.
Maybe this can help:
(https://stackoverflow.com/questions/49284547/gstreamer-rtsp-creating-a-pipeline-to-reduce-latency-due-to-rtpjitterbuffer)