A custom wallet to work with touchdisplay on that thing would be awesome!
but that's easy I guess. as soon as we got a android wallet. I think you can install android on Pi's
Android is one avenue, but possibly overkill and less extensible than having it work on the basic raspbian-os. Things like custom built atms, POS-setups, vending machines etc might be possible for relatively low cost through the raspberry pi ecosystem.
On the other hand, the raspberry pi might be missing some essential parts to be reliable enough, as in missing a rtc and maybe lacking in power for good encryption and such.