https://www.iso-country-code.com/
Iso-country-code - List of country codes in ISO 3166-2 format
ISO Country Code provides a comprehensive list of country codes standardized to ISO 3166 standards in 34 languages, including two-letter, three-letter, and...
iso country codelist of3166 2codesformat
https://wpml.org/forums/topic/adding-country-code-pairs-instead-of-language-iso-code/
Adding country code pairs instead of language ISO code - WPML
May 21, 2025 - Background of the issue: I am trying to add new custom language pairs using country codes instead of language ISO codes on my site
country codeaddingpairsinsteadlanguage