The issue as I understand it is opening a trade agreement with the EU and maybe participating in the Schengen Agreement, not ceding sovereignty. They have had enough of that.
Do you really believe they can be allowed to be a part of Schengen agreement? Brussel is not that insane to open borders to a nation of prostitutes travelling to India and Mexico to escape poverty.
As for a Ukrainian capacity to trade with EU I have pretty much summarized earlier. You haven’t said a thing proving that I was wrong.