Hi and welcome to the forum.
The feature you are asking for is already in my to-do list. The app is already sending the environment stats to our server and the history of temps and so on is being stored. But I have not decided yet where and how to render the graphics with the info: in the Android app or maybe in a web app on this site.
I feel that a web app on this site would be more convenient because it will allow me to paint better graphics than on an small smartphone.
What kind of stats and graphs would you like to have? Any suggestions are welcome.
Regards!