I wonder if these restrictions could be circumvented somehow by transporting components in a form which is technically a functioning assembly.

Not exactly what you were getting at, but Ford does something similar with the Transit Connect. It's imported as a passenger wagon with back seats and windows, which are removed in the US.

You may be on to something.

What's inside the box? That's not a box, its a large paper weight. The random stuff inside is just to add weight.

Not in any means that would remain profitable as it would require post-processing from the component manufacturer and then modification before they could feed the components back into the pick and place robots.

I'm not sure that's entirely correct. I thought there was some duty even on complete devices imported into the UK from outside the EU.

depends on the goods.

e.g. most IT related products are free of duties due to strategic reasons. others have a penalty when imported from countries that do allow/finance price dumping.

If you, as a private person, import goods (shipping) into the EU and it's value is beyond 150€, then you don't have to pay any duties except import-VAT (which is usually the same as the VAT of your country, like 19% in Germany). If you take the goods with you, e.g. back from holiday shopping spree, the minimum is even higher.