Licensed Amateurs can transmit digitally on 2 meters using whatever means they want. A commercial product, as noted, has to use readily decodable means (a format that has readily accessible software) but the license gives an individual permission to experiment. That's how all the digital modes were created... they were all experimental at one point in time, and transmitted as experimental modes.
In my research on the Garmin Rino, I found that the GPS locating can only be done on FRS bands (limited to 1/2 a watt) because GMRS prohibits digital transmission.
Sec. 95.193 (FRS Rule 3) Types of communications.
(b) Non-voice communications.
(1) The FRS unit may transmit tones to make contact or to continue
communications with a particular FRS unit. If the tone is audible
(more than 300 Hertz), it must be transmitted continuously no
longer than 15 seconds at one time. If the tone is subaudible
(300 Hertz or less), it may be transmitted continuously only
while you are talking.
(2) The FRS unit may transmit digital data containing location
information, or requesting location information from one or
more other FRS units, or containing a brief text message to
another specific FRS unit. Digital data transmissions must
be initiated by a manual action or command of a user, except
that an FRS unit receiving an interrogation request may
automatically respond with its location. Digital data transmissions
shall not exceed one second, and shall be limited to no more than
one digital transmission within a thirty-second period, except
that an FRS unit may automatically respond to more than one
interrogation request received within a thirty-second period.
So how will Earl pass location data between devices automatically?
The FCC won't approve a device that transmits on 2m autonomously.
Even APRS devices are programmed by ham operators and specifically set up to do what they do. They are not shipped as devices that just go and transmit whatever they want, whenever they want.