It's now been cracked for doing it offline. I was looking for a Guinea pig.

. I had heard it was possible on Skoda and VW. You can do it on Seat as well. The map care nonsense has been scrapped with MIB3. Online you pay, offline it's free but obviously runs later on the six-month update cycle. People find having the in car maps a good safety feature if the Google / Car Play fails, abroad, mountainous areas etc.
Read on from here:
Unfortunately, in the "guest" mode, when I get into the car, I am at "maximum privacy". I'm changing it to "public location". But unfortunately it didn’t
help. I will be in the car in 2 hours and I’ll also try to take a photo of what it looks like on me.
www.seatcupra.net
Particular this link with the VW portal map update age:
Unfortunately, in the "guest" mode, when I get into the car, I am at "maximum privacy". I'm changing it to "public location". But unfortunately it didn’t
help. I will be in the car in 2 hours and I’ll also try to take a photo of what it looks like on me.
www.seatcupra.net
You use the VW download since that's always updated June / November, pick mid-month (Seat and Skoda can publish the updates late so best to not bother with those. Seat doesn't have the November release at the minute, VW does). What is critical is to follow the VW instructions if using a MAC, Keka and CleanMyDrive on the USB once copied, must be used to clear out MAC rubbish characters that will fault the process. Mib2 High requires the same rigour if using a Mac. For a PC use 7-zip. Use the VW instructions in any case. They are the same across Seat and Skoda. All the same map file for mib3.
The Mib3 unit won't tell you there is a
problem if it fails the validation due to extraneous characters created by Mac hardware (signature check), that's why
if using a MAC you must use Keka and CleanMyDrive. The process should take about an hour of constant power to the infotainment unit + a bit more to catch up from where it left off. Turning the ignition off and walking away, each restart will slowly total to an hour or so. The release number will change when updated as shown on the link. I will write a
resource. You just leave the drive in and wait till after the cumulative amount of live power to it does finishes the update.