EU can’t enforce laws outside their legal jurisdiction. So I guess if you somehow trick Apple into seeing your phone as operating in the EU, then this would work. But I don’t know how you could do so if you use a cellular data connection.

So if I buy a phone in Europe and get it all set up then Apple will remove functionality when I return to the States?

It would be very easy to do. They already control what you see on the app store depending on your locale.

I’m not saying it’s a certainty. I don’t think it would be fair to do to EU citizens traveling in the US on vacation, eg.

If you base it on the App Store account that handles both cases pretty well from Apple’s perspective.

US users can buy all the EU phones they want, with a US account you’re treated like every other American.

EU users can buy a phone anywhere and since they have an EU store account they get side loading.

Where the phone was purchased from is irrelevant. All that matters is the verified payment address.

IIRC this (iCloud account address) is how Apple decides whether or not you are a Chinese user for purposes of Chinese regulations.

This doesn't currently exist, so it's entirely hypothetical speculation.

Look at already existing geo blocking systems. It always depends on the implementation.

Can you buy a cheap DVD somewhere in Asia, and play it at home in the US? No, because the DVD has a region, and the player has a region, and so, you also have to buy a player where you buy the DVD.

Netflix has another system, it checks in real time. You get the content of the region your client connects from. If you fire up a VPN, you get the catalogue of the region your VPN server is in (if Netflix lets you connect, that is).

They'll likely use the same system they use to limit health features in jurisdictions where it's not approved (e.g. ECG).

Oh good point, they do already have to do this don’t they.

There are a lot of regulatory requirements that change by region. Besides health regulations there are spectrum regulations, privacy and data governance regulations, and heck, in China the entire iCloud infrastructure is completely different.