[GlitchMr]

> I'm sure Google can send a cease-and-desist to all sorts of other stores instead of just Apple.

Google may dislike those applications and refuse to host them on Google Play, but they aren't doing anything illegal, so they cannot do anything about programs like https://f-droid.org/en/packages/org.schabi.newpipe/ on other stores.

> This would be breaking the sandbox model of the system, I don't think the regulation requires dismantling system security

I don't think it is breaking the sandbox, it could be implemented using NEAppProxyProvider, however this particular API is not available for App Store applications.

> Programs licensed under GPL as Apple App Store bans those.

iPhone version of VLC is licensed under MPL2 specifically for that reason. WebKit is LGPL2.1.