See, this could do something, far beyond what a grassroots boycott can.
However, I have low trust that the way forward on this is dumping money on local competitors. The reality of it is you can't build a new Amazon where Amazon already exists, you need to remove the anticompetitive foreign agents before you can prop up homegrown ones. There WERE Facebook-like European competitors before Facebook wrecked them. There ARE Amazon alternatives that work just as well in places where Amazon hasn't encroached its insane web of fully owned logistics.
You want to create a European tech alternative? Start enforcing digital antitrust. Not fines, break-ups and forced sales of local branches. If the US can do it to Tiktok the EU can do it to Meta, Amazon, Google and the like.