@SkipH
Google Nest has been requiring two-step verification since May 19, 2020 for all Nest Accounts that have NOT been migrated to a Google Account. If that is your situation, I don't know why you would not receive a verification email; the most likely reason would be if you are somehow inadvertently trying to log onto the Google Nest app with an email address that is different from the one you were previously using.
I don't know if this Help topic will help or not:
https://support.google.com/googlenest/answer/9295081
If you try to reinstall a Google Nest device using a different account without previously removing it from the Google Nest app or Google Home app (and, in the case of cameras and Nest Hubs, performing a factory reset), you will get a message saying the device is already assigned to another account (namely your account). Google Nest has no way of knowing whether the owner of the new account owns the device that is connected to the previous account; that's why removal (and possibly factory reset) is required.
You could also try contacting Support for assistance in straightening it out:
1. Go to https://support.google.com/googlenest/gethelp.
2. Select a category/product family, and type in a brief description of the issue, then click "Next".
3. Click "Other", then click "Next step".
4. Under "Resources", just click "Next step". (Clicking one of the listed links will bring up a Help page.)
45 Under "Contact options", choose to get a phone call or chat with the team, depending on availability in your country.
