Help applying faster R-CNN to mobile

Hi all,
I’m starting out with pytorch, and wish to use detection on Android app,
I understand the new version of torchvision 0.9.0 includes support for Faster R-CNN model on mobile, but I couldn’t figure out how exactly to use it, hopefully like this:
https://github.com/pytorch/android-demo-app/tree/master/ObjectDetection

do i need to trace the model? I’m unsure how to use the fasterrcnn_mobilenet_v3_large_fpn specifically.
Thank you!