The oil pressure gauge is real, though heavily dampened like most modern gauges.
The oil temperature gauge a lot of us have swapped to from the GT350 (or the one built into the cluster) is indeed inferred.
The only option I'd consider would be the OEM Ford tails that were recently released
https://accessories.ford.com/products/mustang-2018-2022-ford-performance-clear-tail-lamp-kit
https://www.lethalperformance.com/ford-performance-clear-taillamp-kit-2018-2022-mustang-m-13504-mc.html
I very much doubt they are remotely accessing the car through the cell connection. Safelite probably connects a device to the OBD port for remote programming.
I learned this the hard way when refueling a diesel rental in Scotland while jet lagged. Put about 4 gallons of unleaded in before noticing.
Sorry to whoever ended up buying that Astra after it was retired as a rental!
Mileage is stored in the cluster. You can raise it easily with forscan, but not lower it, so make sure to get one with lower mileage than you have now.