This is somewhat a naive interpretation. Yes, the EU can enforce certain regulations, ban Apple, etc, but not without repercussions. We live in a global trade environment. It really comes down to whether the US administration would find the EU's actions unreasonable and whether there would be economic repercussions in turn.
A trade war is the last thing the EU wants, especially when they are completely and utterly dependent on the US for technology and protection, so it's very unlikely that the EU will get all extreme on Apple or other US tech companies.
It will push as hard it can but we will not see a protracted ban. The EU understands that it can only push so hard before it starts a trade war and harms itself out of spite.
They'll not ban anyone, the DMA allow fines up to 20% of the international revenue. I think there is enough room to enforce rules without banning anyone.
Sufficiently high fines are no different from a ban. The DMA will never actually fine at 20% because companies would be forced to leave, triggering the above scenario.