You can use Macs without iCloud, not iDevices. On Macs you can already install whatever you like.

I assume they have mistaken “iCloud account” for “Apple ID with associated payment method”. In order to use the App Store, you need payment details with a billing address. Apple uses this billing address to decide which region your Apple ID is in for the purposes of licensing, region locking, etc. If they were going to distinguish between EU and non-EU accounts, they would use this.

Also, in order to change regions, not only do you need to add a new payment method with a verified payment address in the new region, you also need to cancel all in-app subscriptions and then resubscribe after you have changed region. Assuming the app and subscription is available in the new region, of course.

I’m skeptical they’ll do this though. Allowing side loading is a sufficiently large change in strategy that it doesn’t really make much difference to Apple if they allow the EU to do it vs the whole world.

This is a market, not immigration/border-security law. So might not apply in the occupied parts of Ireland.