By december 21, I have read, so a while

Make sure that you have NFC on, which is obvious but may not be on. Then, may I ask how you are trying to unlock the door. If you are not, I think that you should try double-clicking the side button like when you would do it by an NFC cash register, as that would transmit NFC data.

Probably you are still invited to the sandbox account. Go to app store connect and delete or uninvite the account

Is your apple developer subscription renewed?

Turn off iCloud keychain, and write down or save the passwords/accounts/etc in iCloud keychain. Then remove the account and turn iCloud keychain back on. Restore files, contacts, calendars, and bookmarks from icloud.com and reenter all of the stuff that you had previously written down/saved. Hope this helps.