[Polylang] Show a post in other languages

I have a multilingual website: it_IT (default) and en_US.
Sometimes I would like to write a post only in English and show the English version also in Italian, not to hide it.
I think a solution is adding a the option of inserting a language code in the other languages fields: if a translation is not available, shows the selected version.
Post Language: English. [Translations Italian: en_US]
The English version of the post is shown also in https://www.mywebsite.com/it/.
An advice may be displayed:
This content is not available in %s. The %s version is shown.

If the multilingual website has more than two languages (i.e. it_IT (default), en_US and fr_FR), and a post is not translated in some languages (i.e. fr_FR), I can choose to show a specific version:
Post Language: English. [Translations Italian: en_US, French: en_US]
or
Post Language: English. [Translations Italian: en_US, French: it_IT]

Also a “list_available_languages” option may be added.
Post Language: English. [Translations Italian: it_IT Post Title, French: list_available_languages]
An advice may be displayed:
This content is not available in French.
You can read it in another language:
– Italian: “it_IT Post Title”
– English: “en_US Post Title”

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