On MicroOS only the en_US locale is installed in glibc. Therefore the current jeos-firstboot code does not offer to select a locale and assumes en_US. There are follow up dialogs to select a keyboard and time zone though. Normally those lists pre-select a sensible default based on locale. Especially the keyboard selection is rather annoying as there are e.g. a lot of German keyboard layouts but mostly only de-nodeadkeys makes sense.

So I wonder how usability could be improved. One way could be to just show the locale selector based on live-langset-data and put an explanation text and maybe asterisk on not actually installed locales. glibc-locale could be installed based on too after all.

Or maybe only show keyboard layouts that are also in the langset data? That would be congruent with how locale selection works.

Last but not least maybe it makes sense to split glibc-locale to only include the locales we actually show in the installers?

localhost:~ # ls -1 /usr/share/langset/|wc -l
59
localhost:~ # ls -1d /usr/lib/locale/*.utf8|wc -l
151