I received my Nitrokey 3C NFC and currently add the security key to my accounts. I’m using Firefox 94.0 on Ubuntu 21.10.
I could add the key to all sites (e.g., Cloudflare, Github, Gitlab, etc.) as expected, only Google 2FA does not want to cooperate.
When I click on “ADD SECURITY KEY” in “2-Step Verification”, I’m asked to insert the key and then tap it (this is when the green lamp turns green/orange(?)), and after the tap I only get “Something went wrong. Try again.”
If I try to add the key on my Android phone in the same dialog using NFC, I get the same error message.
I also used https://webauthn.bin.coffee/ to check whether everything is working, and it indeed works: Create Credential and Get Assertion gives me all green.