How can you export keychain passwords

See the article Copy keychains to another Mac - Apple Support

Note: You can’t copy passwords stored in your Local Items or iCloud Keychain. To transfer these keychain items to another computer, set up iCloud Keychain on the other computer using your iCloud user name (normally your Apple ID) and password.

Read Import and export keychain items using Keychain Access on Mac - Apple Support

Note: You can’t export passwords from Keychain Access.