We have a website that serves content for New Zealand and most of the world. The same content is picked up by another subsidiary website and served to the UK, with our permission.
We would like Google to see the NZ website to be the primary site for most of the world, and most importantly for New Zealanders. However, only in the UK, we would like Google to see the UK site as primary.
I believe I understand the correct way to use hreflang in this scenario. We would set up an hreflang=en or hreflang=x-default for the primary site, and an hreflang=en-gb just for the UK site (and obviously take care to get all the technical details correct, such as having both hreflang tags on both sites, using absolute URLs, having self-referential canonical tags, etc).
My question is not about the theoretical rightness of that solution (although please correct me if it's not right), but about how well it will work in practice. Specifically, we're worried that many New Zealanders will set their browser and/or Google language settings to "en-gb", just because it's often the default, and most people can't be bothered to set these things up perfectly.
Does Google pay attention to those settings when deciding which hreflang alternative to show? Will a lot of New Zealanders end up getting shown the UK version of the site?