It's possible, but not a simple thing to do. There's no "global" event handler, so you'd need to, in every control that the user can interact with, update its OnSelect (or OnChange) property to update a "last activity time" with the value of Now(). You'd then need to have a timer that every minute checks the last activity time, compare it with the current time, and if this time is greater than 10 minutes, exit the app.
The timer properties would probably be along the lines of this:
Duration: 60000
Start: true
Repeat: true
OnTimerEnd: If(DateDiff(lastActivityTime, Now(), Minutes) > 10, Exit())
On each button, which will likely have some action on its OnSelect property, you'd need to update it to also update the last activity time:
OnSelect: Set(lastActivityTime, Now()); <previous OnSelect action>
Likewise, in all text inputs, you'd use its OnChange property to do the same:
OnChange: Set(lastActivityTime, Now())
In all other controls (slider, rating, listbox, anything where the user can interact), you'd need to have a similar action to update the last activity time.
So, while it's possible to do this scenario, it's a lot of work. If you feel that this should be supported natively, please consider creating a new feature request in the PowerApps Ideas page.
