If Apple can't work out a legal structure that work, it will be forced to refund for the devices

How is that going to happen if the US attacked Europe?

EU freezes/takes over all Apple assets in EU, users with Apple devices get the money in cash upon delivering their devices. If the money isn't enough for the refunds, a finance mechanism can be created that will be settle after the war.

The returned devices may be sold to 3rd party markets if Apple isn't cooperating.