> Is this USA only? There are postal codes/zipcode-equivalents in other countries.

This is where the real problems start - postcodes exist the world over.

Speaking as someone that has dealt with countries that have postcodes, but no states, so it's just Street Address (if applicable) | City (if applicable) | Country | Postcode

Inputting a "zip code" first would result in every country being in the drop down.

In Australia, addresses too are wild, they should be considered "free form"

https://blog.melissa.com/en-au/global-intelligence/australia...

Gives this as an example address The Smith Family

'Willow Creek' Station

via Winton

QLD 4730