Sorry for the delayed response but could you provide more information about your concern so I can take a look into it? What exact Nest device are you trying to add to your Google Home app? Are you getting a message or a code when doing so? If yes, what is it? It would also be a great help if you could provide a rundown of the steps you've already tried so we can pick up from there.
Glad to hear that it worked on a different email address and thanks for your patience in trying those steps out.
To answer your question, GSuite or Google Workspace is a subscription-based premium service of Google designed mainly or small business to enterprise owners for complete set of office productivity apps including emails. You may check more of that here: https://bit.ly/33WQ8ls
Going back on deleting an account from the Google Home app, please follow the step by step guide on this link.