I've looked through the API and it's all for Facebook Pages to set up a Chatbot. I wanna be able to set up a Webhook/Listener for chats/messages on my personal profile (to mess around a little).
I'm asking cos I can see unofficial Messenger apps on the Play Store, and they don't look like just a web implementation.
No, there is no way to do that using the official APIs.
Read access to user conversations has been removed a long while ago already, and there is no webhook functionality for this either.