You should boycott evil corporations regardless of where they are from, don't make it a nationalistic thing, some of the alternative suggested here are as much bad as their usa counterpart. You are not achieving shit by switching from nike to adidas...
The last line on the document says "Perfect is the enemy of good. Every little bit counts."
It's pretty apt. To deal with this particular issue it makes sense to divest from one country to another regardless of brands. Divesting from mega corporations is another issue entirely and beyond the scope of this boycott.
It shows the USA that the people care enough about this specific issue to spend their money elsewhere.
The issue of mega corporations is completely separate of the issue of the USA. It would be best to deal with both, but it's better to deal with one than to do nothing at all.
No you see, when the workers are locked in the burning production plant, it matters a lot if they are are murdered for a billionaire who avoids taxes in the EU, as opposed to a billionaire avoiding taxes in the US.
Afaik its about decreasing reliance on American goods and services due to their tarrifs on the EU, those products and services may not be available in the future so its better to find solutions now then scramble later