Until quite recently I didn’t know this locale existed, but I use the ‘en_NL’ locale in KDE Plasma. It’s exactly what I needed and it’s amazing.
However, I can only use it in Plasma, and after I’ve logged in. I can’t figure out how to set it up system wide so that SDDM and all the other systems can use it.
locale -a does not list the locale. It does list a few *_NL, nl_*, and en_* locales, but those either translate things into Dutch or change things using weird formats (such as dates and time).
find / -type f -name "*en_US*". Searching for files that define locales also didn’t do much for me. Trying to find something that defined en_US.UTF-8, for example, resulted in nothing I could use.
I think the main problem is is that it isn’t an officially supported locale, see: 14085 – en_NL: new locale (English language for the Netherlands). But, the locale I use exists and it exists somewhere on my system. Does anyone of you know how I use this locale system wide?
Edit: I forgot to mention I use Fedora 35 KDE spin.