My answer was generic. Some companies only offer a stop on round-trip booking. 20 minutes is a common limitIn the past, I have booked Tiffany Towncar one way (from MCO to hotel) numerous times and have always gotten a 30-minute grocery stop included in the price. I have never needed to book round trip to get the grocery stop included.
I have not travelled during the Pandemic so I don't know if this has changed.
It appears Tiffany still offers a 30 minute stop even if you booked a one way transfer.