The US and EU have a good relationship. The EU can (probably will) use international law to hold you accountable and the US is likely to comply.
EDIT: you is the hypothetical you. If the EU targets you then they will use international law to do so.
EDIT: you is the hypothetical you. If the EU targets you then they will use international law to do so.
If you literally don't do any business with EU entities, even at arm's length, enforcement is going to be impractical and unlikely.
However, that seems like a very arbitrary line and governments love to waste money.
I don't have an answer but I suppose we'll find out soon enough.