I hope the above site helps with the question.
As I live in Australia, I must purchase the ISBN's from the Australian Agency, and I must register my publication with the National Library of Australia (and the state I live in, although that has recently changed and the two are being merged into one legal deposit req.).
Selling on international markets is done through (usually) an aggregator/distributor like IngramSparks (or Amazon, or similar). The ISBN is International Standard Book Number, so the numbers for each country are slightly different, and for those who know how to read it, they know the originating country (What is an ISBN? | International ISBN Agency
There's also this: ISBN for Self-Publishers: Answers to 20 of your Questions
It's always worth checking the req's with the ISBN agency in the country where you publish the book (ie where you are resident, also worth checking what this means as to whether you are a temporary or permanent resident).
Caveat: Things change. I always check.