They're right, Apple are playing crybaby -- in particular not allowing alternative browser engines on iPad because it's not 'iOS.' What a ridiculous move.
I've vacillated between supporting EU and Apple in this scenario because I understand both perspectives. Ultimately I think our devices should be as free and open as the end user sees fit.
If Apple were *motivated* to support more app stores and browser engines, they could figure out an elegant way to do so whilst remaining competitive. If this EU system seems clunky and disjointed, know that it's because Apple have intentionally made it so. We live in a world where you have to pick between Android or iOS. Period. Anyone claiming you can simply choose not to use those devices is not a serious person. Apple and Google cannot have a totalitarian say over what these devices can and cannot do.
Look at how many devs choose the Mac App Store when other app stores and independent release systems exist. They choose it because it's genuinely a good option on both the part of the developer and end user.
Also "security concerns" regarding alternative app stores sound mostly unfounded considering what makes iOS devices secure and private is the sandboxing and permissions system which works on a system level, Apple 'reviewing' each app that gets submitted to the App Store is mostly to check for content violations rather than malicious code I think. See macOS as an example and that's an even more difficult system to keep secure/private because software can optionally run helper processes at a root level.