You can install alternative app stores on iOS (within the EU). AltStore, Epic Games Store, and even a corporate-targeting store from Mobivention.

Apple is pulling some shit that will probably be declared illegal the moment it hits the courts with installation fees when distributing apps outside of Apple's ecosystem, but AFAIK Epic is taking care of that for AltStore and Mobivention probably factors it into its corporate pricing structure.

There's a lack of apps on these stores, though.