Fallback to default language

I was wondering what would be the best practice to create a fallback to the default language for certain post types.
Example plugin: https://github.com/helsingborg-stad/polylang-fallback/

Case:
The default language for all content is English. When a user is on a different language I would like to still show the English posts if there is no translation available.

Thanks in advance!
Regards, Jory