Q: How can I verify my iCloud keychain if I don't have access to my old phone number? Is there another way to verify?

Hey k1drob,

The article linked below details what to do should you not be able to access your old phone.

If you can't access a device that has iCloud Keychain enabled, contact Apple Support and verify your identity to get help setting up iCloud Keychain.

Get help using iCloud Keychain
https://support.apple.com/en-us/HT203783

Sincerely,

Allen