We already can - in light aircraft form they’re called SkyBeacon, TailBeacon, and TailBeacon X.
There is a difference between a position source device and a navigator. This item, whether encased in the ‘Beacon’ series products or as shown here as a GPS product, is only a position source. In other words, its only output is a latitude/longitude fix and maybe a time stamp.
It doesn’t know where you’re going (doesn’t know your flight plan or destination). Doesn’t have a database of airports or waypoint or procedures. As a result, it can’t provide any left/right deviation signals.
I’m not criticizing the product. Just saying that this is not a replacement for a GNS or GTN or IFD unit. A position source isn’t a navigator.
uAvionix already builds a super nice little portable battery powered ADSB In and Out unit for about $600 or so. Unfortunately, is is not approved in the US. You can use one as an IN only but must turn off the OUT function. I had one in my Aeronca Chief until I sold it last year. The Chief was non electric and could not operate a certified ADSB OUT unit. It just suction cups to the windshield and fed the IN data to my WingsX iPad. Was great. And…I did “test” the OUT frequently. ATC could pick me up but with a slightly different electronic display, and other aircraft could see me on their IN. Research with my FSDO indicated the FAA had no issues with this unit. It was an FCC refusal to approve issue. Google Sky Echo 2. Sentry sells an IN only device that is identical in appearance to the Sky Echo 2. I assumed uAvionix is building it for them. While "testing " my Sky Echo 2, I did feel a bit more secure in that other IN aircraft around me could now see me…since no one is any longer looking out the windows.