Lets Throw out this crazy idea for consideration: Drop support for all countries.
To start off this will not actually be completely possible because of broadcast regulations, but if you limit it to wireless networking (and other radio application) configuration, we can then define a country as a broadcast regulation scope.
This leaves a number of localization issues, starting with language, but language is already cross border in many cases. Language is also asked as the first question so it stays the first question. In many cases number format can be derived from language, and in those cases where it cannot there is a significant group who needs to deal with multiple number formats, so separate question.
Dates and times are a major issue (aside from time zones which both divide and span countries) date names tend to come from language but date order does not and this provides a good excuse to standardise on year month day as the default (of course allowing user customization, but there are fewer ways to format a date than countries).
As far as I know Debian does not have any configuration of measurements (aside from paper size and display resolution) but this is becoming less of an issue as there are no longer any international differences in the definition of an inch (although some countries have multiple definitions) and meters and inches are hard to confuse so this is getting simpler by the year.
Mirrors and be grouped by city, which works better for both big countries (with multiple geographically diverse mirrors), small countries (that may not have a mirror) and border regions (the closest mirror may be in another country) and there are multiple efforts to have automatic mirror selection, so with private mirrors, this comes down to three choices: use a mirror network, pick nearest mirror, or use a private mirror.
I have probably missed other localization issues, but by and large we can just treat them as configuration issues and the only time a country name comes into play is when dealing with the few configuration issues that are regulated by statute making the list of countries not an issue of local pride but of laws accommodated so a country only needs placed on the list if there is a regulation to be accommodated and the list gets much smaller.