I've seen this in the news lately, a proposed merger similar in style to the European Union between the UK, Canada, Australia and New Zealand. According to some polls it has over 50% support in all four countries with Canada in the 75% range. I don't know enough about the logistics of something like this, but it sounds interesting and I don't have any reason to oppose it.
https://globalnews.ca/news/3975037/push-...-britons-and-australians-gains-momentum/