Basically, this thing which was never made for the US market.
I suggest the codename ‘project open sesame’ if this is approved for development.
Physically, device would be a numeric keypad, outdoor rated. Battery power or option for 9-24v AC/DC. Much like a smart lock, user codes could be loaded from a hub (and it would probably appear as a smart lock to the hub). Also have a large doorbell button. There’d be a relay to bridge the two power terminals (or another two dry contacts).
Use case- a big one would be garage doors. This could be hardwired into the garage door (and get power from the door), or would use an existing z-wave garage door controller unit. That would give far more functionality than a normal garage door keypad as it could be automated+connected.
For a garage door, this could BE a garage door controller, with the addition of two magnetic contact switches for fully open and fully closed. That would require some intelligence on the hub. For a garage application, the doorbell button could turn on the garage light for example (user programming of course).
This could also be a smart lock door controller. For someone that doesn’t want an external facing smart lock, and gets one of the inside-only retrofit kits, this could open the door. It could do double duty as a doorbell in that application.
Firmware- obviously smart lock functionality (set user codes), with status report (report when correct user code punched in, perhaps report when each button is pushed), and scene control, and battery status. Tamper switch might also be good.
Relay would be user configurable- click power terminal relay on successful code entry, click secondary terminals on successful code entry, click either one on unsuccessful code entry, click either one on doorbell button push. All disabled by default.