I haven’t seen or used that before but there are multiple potential problems with it and it seems like an accident waiting to happen.
First, it specifically says not for use with EVs.
Second, you are taking two 15A circuits and combining them into a 50A circuit? It doesn’t work like that. The wiring is still only capable of 15A (maybe 20A depending on the circuit.) You theoretically could get 30A off of dual 120V circuits but the setup assumes proper current balancIng. If you’re running on GFI circuits (which you should be in a garage) any current mismatch will cause the GFCIs to trip.
Third, you would need to plug each of the 120V plugs into an outlet that was on a separate leg of your service to actually get 240V meaning you need two 120V receptacles on different legs adjacent to each other. Odds are you won’t have this so it won’t work without rewiring or adding a circuit, in which case you might as well do it right.
If you read the description carefully, they state the wire and connectors are UL approved, not the device. I would steer clear.