Unable to access husband's Apple Account due to unreachable email and lost devices

In a longtime Apple family, I am now the only computer user. I need to open my husband's e-mail as an apple account (he has an e-mail address for apple, but his old address at gmail.com is no longer reachable). His Apple computer no longer works, and he has lost his iPhone, so I cannot access any accounts to get verification texts or "start over," adding his e-mail to my iPhone and my MacBook Pro. Help!

He wants to simplify his computer life as he is dealing with cognitive issues, but we can't seem to break into his old compuer presence on Apple to consolidate where he gets e-mail. Especially affected are health records, that typically do not permit two patients on one e-mail, so we mjust have two accounts.

[Re-Titled by Moderator]

Original Title: Bringing my husband's email under my Apple account. We do not have access to his old gmail, and Apple insists his latest pw is wrong....but I have no machine to receive verification.