Apple switched to USB-C because making separate hardware SKUs to comply with the EU would be costly. Even then, they only did so after creating a new standard and accessory ecosystem to replace lightning port revenue (MagSafe).
When it comes to allowing third-party app stores, Apple is only going to do that in regions where law forces them to do so.
Apple already had and has multiple hardware SKUs for the iPhone to support different regions, for example the US phones have no SIM tray while other areas still did/do.
They were already using USB-C on the Mac and iPad so I don’t believe the EU mandate forced anything but maybe the timeline.
That said, I wouldn’t be surprise if side-loading is limited to the markets where it’s required.
From what I understood Apple will allow third-party app stores soon due to EU regulations, and is already (reportedly) in process of making that happen.
Apple switched to USB-C because making separate hardware SKUs to comply with the EU would be costly. Even then, they only did so after creating a new standard and accessory ecosystem to replace lightning port revenue (MagSafe).
When it comes to allowing third-party app stores, Apple is only going to do that in regions where law forces them to do so.