You have a good eye! It certainly does look like a removable panel from the inside. This may or may not become an optional or standard feature for rear SUV panels. Has anyone seen any official statements about such a feature?
Installing a sunroof requires cutting both the roof panel and the headliner. Core swap of just the roof panel (likely bonded to the frame) would not include the headliner. Aftermarket sunroofs are available professionally installed at local vehicle customizing shops nationwide.
Aftermarket sunroofs are always an option, for any vehicle. DONMAR has just the right fit for what you had in mind. We are in contact with Slate as well.