I want to include to include two sets of countries in the post configuration of my posts such that people can search for content by country or citizenship. How do I do this with or without using categories as the organizing framework?
I can't help you with your question, however, I saw you were wanting to make a countries list. I spent a ton of time putting one together in a types select field -- There's something like 248 countries. To help you out and so you don't have to reinvent the wheel, I'd be happy you send you a module for your use.
I also have the US and Canada in the same format if you want it.
Here's a couple of images of how I have it set up.
The problem then is is using it as a selectable search filter field in View. Normally, it displays as checkboxes on the frontend as well. But I want something similar to the box in the first picture above. If I can't achieve that, this would almost be useless to me. I want users to search by countries but fron the backend, I need need to be able to associate the same scholarship with many eligible countries.