In Denmark we are like: Need a domain for our common ID and login system? How about nemid.nu, where .nu is the TLD of Niue, but "nu" means "now" in Danish, so lol, let's use that. On top of like 7 other domains that users are randomly redirected between during use.
(Unlike with almost every other ccTLD, UK is also not the ISO code for the country—GB is—and is instead “reserved”, which is why I must struggle to remember each time that the BCP 47 for Ukrainian-in-Ukraine is uk-UA.)
The sad fact of the matter is that structured and controlled ccTLDs where you knew what you were dealing with from the name alone are increasingly being supplanted by second-level domains.
When the TLD .au arrived, .oz was renamed .oz.au. So my email address at Elec Engineering at Melbourne University was <name>@ee.mu.oz.au.
And then a few years later, the third-level structure got formalised. Melbourne Uni, for instance, switched from mu.oz.au to unimelb.edu.au.
I for one missed the typographic economy of the ee.mu.oz.au domain.
None of this really matters, of course, except that a sensibly designed structure with a clear underlying rationale, and historical context for a small number of exceptions, makes everything easier to understand :)
Another bit of historical trivia that now becomes mundane: csiro.au.