I can only speak for myself, but the reason why I went from my Note 2 to the Nexus 6p was stock Android, and avoiding all the extra bloatware that phone companies like to add.
Unfortunately, I am now regretting that decision, and I should have done a better job back then getting information around Google Store and its return/refund policies.
As far as I can remember from my time there, a valid UK address was mandatory in order to open a bank account there, but maybe this is no longer the case (or it isn't for the banks you mention).
I bought in the UK and then moved to Canada. Google refuses to replace the phone (since they no longer have it in stock), and they claim they can't refund me since the payment method I used to buy the phone (an UK Credit Card) is no longer active, and I don't have an UK bank account.
I am on the same boat. I really love the stock Android experience, and before this issue I was suggesting it to colleagues and friends, and I was considering to possibly upgrade to the Pixel 3 later this year (at least if it lives to the expectations).
After this though, I think I'll look somewhere else, possibly with a company that offers a better customer support.
Unfortunately, I am now regretting that decision, and I should have done a better job back then getting information around Google Store and its return/refund policies.