You would have to setup a proxy server or port forwarding on your infrastructure so you can capture all network traffic that is coming from your phone.
Then you would have to look at that network traffic capture with tools like wireshark and filter out all traffic that is not related to Pokemon Go (Your Facebook, Your Reddit, Your Youtube etc.). Then when you have filtered this traffic you will have to check the remaining traffic for new content which is really hard because in the capture you have defragmented packets that don't show the content that is transmitted.
Imagine the network is a small tube and the Pokemon Go App ressources are several large puzzles that are transfered from Niantic to your phone.
Niantic is taking the puzzles apart and sending the puzzle pieces to your phone. This happens in random order.
On the back of the puzzle pieces there is a number that indicates to which puzzle the pieces belongs and how many pieces there are.
If your phone is missing a piece it can request the missing piece again from Niantic.
What you are asking for is how to make a hole in the small tube and check if there is a new large puzzle we have not seen before. You would have to check all the puzzle pieces and put together the puzzles to see if there is a new one.
The problem is that puzzles are transmitted several times (for example the model for a dragonite in your pokedex).
So you will need a lot of time to check if you have already seen the puzzle or not.
Also you don't know if you will have all the pieces because maybe you cut the hole in the tube after the first puzzle pieces already were sent to the phone. And you don't have the possibility to request missing puzzle pieces, because you only can look at the pieces but not interact with Niantic.
I hope this makes it a little bit understandable that this means a lot of effort and is not easy to do.
So to whomever is doing the network traffic analysis for the HUB:
GREAT JOB MAN