I am not at all familiar with the business model between Facebook and Oculus, I'm guessing Oculus is operating as a separate business entity.
As far as I know, Oculus is a wholly owned subsidary of Facebook now, not a separate entity.
However Oculus products have been taken off sale in Germany precisely because being forced to use a separate product to use another product isn't allowed - it's called coupling. It can be argued, that at least for Rift, Rift S and Quest that didn't originally use Facebook accounts, that forcing them to use a separate product to continue to use their devices is against consumer law as you are changing the basis on which they were purchased in the first place.
The situation with Quest 2 is somewhat more difficult as it says 'Requires a Facebook account' on the box. Though authorities may take a dim view of a company forcing users to use a social media account for a gaming device.
Generally where Germany leads, the EU will follow, so it'll be interesting to see where this goes. This is on top of Facebook threatening to leave Europe altogether, as Ireland is taking legal action against Facebook to try to prevent them sharing user data with Facebook's US servers.
Though that does have massive implications, because a lot of services, including gaming services share info with US servers - Steam for example.