Hyundai and Kia added official GrapheneOS support to their apps months before Volkswagen banned GrapheneOS:

https://discuss.grapheneos.org/d/31697-myhyundai-app-has-official-grapheneos-support

Pressure from Volkswagen customers on them can achieve the same thing. There's no legitimate reason to ban GrapheneOS so they'll undo it with pressure.

myHyundai app has official GrapheneOS support - GrapheneOS Discussion Forum

GrapheneOS discussion forum

GrapheneOS Discussion Forum
@GrapheneOS I've been working as an external consultant for Volkswagen and they can't tell their arse from their elbow. No sane decisions will be made in their companies. (Nothing against the DEVs there. Fine people. But their management could fill several volumes of Dilbert-comics.)
@n_to They'll change their mind about this after their app gets tens of thousands of legitimate 1 star reviews and their customer support system is thoroughly clogged with legitimate support requests from their customers demanding compensation for banning GrapheneOS.