What $249.99 actually buys
The box contains the ELD and a 6-pin J1708 adaptor. The device connects over 9-pin J1939 or 6-pin J1708 and pairs by Bluetooth to a phone or tablet running the free Garmin eLog app, or to one of six compatible dezl navigators.
It is not an OBD-II device. Garmin states plainly that the eLog is not compatible with vehicles using the OBD2 protocol (SAE J1979), which rules out light vehicles.
Volvo trucks using the 16-pin J1962 connector need a 16-pin to 9-pin adapter that Garmin sells separately and does not price publicly.