Apple has already tipped their hand with how they will handle side loaded apps.
techcrunch.com
Apple has positioned and viewed iOS devices more like consoles than PCs, and I expect them to continue operating in that manner. The EU law is poorly worded and gives Apple a lot of leeway here.

Apple to charge 27% fee for Dutch dating apps using alternative payment options | TechCrunch
Following a court order, developers working on dating apps don’t have to use Apple’s in-app purchase system in the Netherlands. And because those

Apple has positioned and viewed iOS devices more like consoles than PCs, and I expect them to continue operating in that manner. The EU law is poorly worded and gives Apple a lot of leeway here.