If someone here could post statistics on the number of visitors by country, I'd be happy to make a list of sub-divisions for the more popular ones (and get their flags). I used to play with maps a lot and sub-divisions were fun.

I made this fairly quickly: https://docs.google.com/spreadsheets/d/1p6A02pCwV5M2s95N67vrruMlpMRDASxIX75EczfQ2dE/edit?usp=sharing

The SVGs can be scaled without loss of quality, which is nice. I can make small versions of the flags later if you want, unless you want to do them yourselves.

Whoa, wait a minute, was it my internet being bad or were flags added recently to countries with subdivisions that didn't have any icon?