Deep Learning Model(CNN) Question on pynq

Hi, I have seen many papers about using pynq to accelerate AI model such as CNN.
I want to create my own CNN model using pynq overlay to achieve accleration.
I have download Vitis AI to run some example with its overlays.
These are the problems I am confused about:
(1) Can I retrain these model such as yolo included in VITIS AI with my own dataset?
(2) Even more, can I build my own model using CNN with overlay on the board using tools like REVISION or other tools?
The board I use is ultra96 v2.
Any advice will be appreciate!
Thanks for your helps!