I have one myself and would love to see where the cat is in the home assistant UI.
I managed to set up mitmproxy and log into the sure app with this and was able to capture the raw data.
There is nothing to share at the moment and so far i have only experimented a little bit.
Getting any further would require being able to authorize a connection to sureflap, and getting the id’s etc. The app doesn’t use mqtt, but rather http.
e.g. https://awshost/api/timeline/household/