"Without naming the machine's maker"
Not many cars around that use apps to control them .. dare I mention Tesla? The procedure for transferring ownership is pretty hard:
Log out of the app
Inform Tesla of the transfer of ownership and also send a copy of the registration
New owner is required to inform Tesla of:
Colour copy or photo of current driver’s licence
Copy or photo of vehicle registration
Email Address (the email use for My Tesla Account)
Home or mailing address
Might be easier to buy a much older car that doesn't have apps to control it.
(PS: I'm a Tesla owner)