If you use a password manager like Keepass, you should still be able to log into your other accounts if you lost access and at least with financial institutions you can call, ask that no changes be made with without coming into the branch and showing ID.

Yes, but many companies will also drag their feet, refuse for "security reasons", or you'll just never be able to reach them in the first place because their only support is an AI concierge that tells you the same thing over and over.

As an example Anthropic and OpenAI don't let you change your email address.

If you use a password manager like Keepass, you can put your TOTP into it as well. With both a password and a keyfile it's still two factors, technically.