Tbh there are more issues if they wanted to be compliant with EU regulations. I'm fine that they aren't compliant (they aren't in the EU, after all), but it's something to be aware of when ordering from them.
Seized by customs because they don't offer 2y warranty or include USB charger?
No. That's ridiculous. You can import whatever you want.
Quite the opposite, in fact. When customs finds that any rule, like the CE declaration on electric devices, is broken, they can and will seize such goods.
You could of course attempt to circumvent or mislead customs. After all, they don't have the capacity to check all imported goods in-depth. That however would usually be a criminal offense.
No, you can't. You can import whatever you are allowed to import, regardless of it's legal status on the original country.
They don't have to do business in EU if they don't want to follow the rules.