Hi,
Please check the suggestion in
Profiling CPU/GPU Usage in ROS 2 Camera Node on Jetson - #5 by DaneLLL
Since you need to send CPU buffers in BGR to appsink, have to convert NVMM buffers to CPU buffers so some CPU usage is expected.
The nvv4l2camerasrc plugin supports UYVY. It is open source and you can customize it to support YUYV(named YUY2 in gstreamer). We never try NV16, so you may give it a try but result is unknown. Would suggest use YUV422 formats such as UYVY or YUYV.