Hmm. That's a good thought. IIRC fontconfig on Linux can merge different fonts with different priorities, so I think that someone could make a "flag override" font that has extra-wide emojis and has both the ISO code and the flag, even without changing the original font.
While we're talking about Austria, if we're going to a subnational level, check out the Austrian state flags. Over half of them are just a red-and-white horizontal stripe:
Also
🇧🇻 🇳🇴 🇸🇯
"These are all the flag of Norway" you might say, and that is correct. But one is for Bouvet Island, one is for Norway, and one is for Svalbard and Jan Mayen (in that order, here). Norway's national day was recently and it is fun every year to see so many people celebrating Bouvet Island (it shows up first in alphabetical lists).