As someone who lives in Portugal which already stops every single package you get from outside EU with no exceptions for a decade or more:
I can tell you how this will go
From now on if you receive a package from outside EU, it'll first go missing for weeks and nobody will know where it is, then you'll receive an email from your country's customs agency
They'll make you login to some extremely unusable and outdated web portal which breaks half the time and where you have to classify your shipment in one of 10,000 confusing category codes
Depending on the category code you'll pay a different tax rate, sometimes it's 5% sometimes it's 60%
Then you have to pay the customs duty in some archaic way that will also be broken half the time
And then you'll finally receive your package from outside EU after months
Experiencing this for a few times you'll realize you will never ever try to order or receive anything from outside EU ever because the ordeal is too painful and expensive
I get asked a lot here by people from US to test out new products (like the guy who made the Minimal Phone) and it's just literally impossible for me to receive it even for testing. I tried to classify it as samples for testing but you need to go through a bureaucratic process of insane lengths to get that through so I just gave up
Realistically all this does is make Europeans live even more in the stone ages, as now they can't use modern AI, nor get modern products from outside EU because it'll be too much hassle to order