I'm wondering what could be not obvious consequences from the user experience perspective if I'll choose to go with default language for UWP application as "en" instead of "en-US" and provide localized resources only for "en" culture, but not for "en-US".
Considering that there is not much text in the app I'm assuming that it should behave in English for, say, US-based users and Great Britain-based with equal experience, but just in case would like to be sure about that.
As far as I know if you leave the default language as "en-US" and provide resources for it the app will fallback to it for, say, "en-GB users", so that's where this question arose - what are the pros and cons to go with "en" or "en-US" for application, that is distributed worldwide?
Any thoughts?
As far as you do not differentiate en languages, there shouldn't be a difference if you choose en-US, en or en-*. As MSDN says:
Windows prioritizes matching of languages in a standard well-understood way. For example, en-US matches, in priority order, en-US, en, en-GB, and so forth.
• Windows does cross regional matching. For example, en-US matches en-US, then en, and then en-*.
Providing en-US and en would make sense if for example you have resources specific only for US, and other resources for the rest of en languages.