I spent the last 15 years looking for nails, because I am the hammer.- Merlin Mann
When iPhone disconnects from a Bluetooth connection with a car, it does a special step to mark the location as "Parked Car" in the Maps app. My 2004 Prius is too old to have Bluetooth connection, so I was wondering if I could replicate this feature. Answer? Not really.
I thought it would be awesome if I could get a little Bluetooth dongle that plugged into the car power port and said, "Hey, I'm a car!" That way anytime I turned on my car, the device would power up and BOOM I would have that functionality, but it doesn't seem like any such device exists.
Next step, can I write a Siri Shortcut that does this? Also, not really, but I gave it go. The main shortcut command, "Get Current Location" provides the address you are at, not the GPS coordinates. If you're in the middle of a parking lot it's just going to provide the address of the place you've parked at and additionally Shortcuts doesn't give you a way to set a marked location / drop a pin. So the best I can figure out is to write out the address into a Dictionary (JSON text file) on iCloud Drive. Then I need a second shortcut to read it and open it in Apple Maps. I also launch Apple Maps at the end of saving so you can manually drop a pin on the current location.