It's not a new discovery.As said here

https://de.motor1.com/news/692207/verlassener-ford-haendler-brandneue-sierra/

the 150 new and 150 used cars were sold by the widow of the owner from 1998 onwards (I also remember articles in classic car magazines back then), only these six cars in the showroom she kept for her childs and grandchilds. But until now -the widow died in 2021- they didn't take them.

What "an expert" says there, is bs, so that the cars have no valid TÜV any more - they never had one, because they are new, never registrated cars.
Which is the main problem, because when you want to bring the cars in traffic, they would be handled as new from 2023 according actual regulations, which makes it impossible.

But at least it may be possible somehow. Time-by-time there are classic NOS cars with new registrations.
There are also some single newer cars, which normally have no chance, which got a registration. So there shall be one ZA origin Citi Golf with a regular German plate, I heard.