I don't think so and this is where unregulated markets (although I am not a fan at all) would push the prices down. If anyone can provide an app store and that app stores fees are lower people will move.

What Apple and Google need to do is work on assuring that Apps can be uniquely identified (which the can already) and validated so that you don't have a clone of an App in another app store.

AIUI China has many mobile phone builders that all use android with minimal customisation, so they're basically interchangeable except for the prices of the vendor-provided app store on each. And apparently none of them use app pricing to undercut the others, unless I've overlooked recent developments?

It's not clear to me why the Chinese competition fails at undercutting Apple/Google and the proposed app store competition would achieve that. I don't see the relevant difference.

The unique identifier on Android is easily broken, BTW. I don't know iOS well, but on android it's simple. IIRC you don't even need an android development kit, the java tools will do. This fine web page lets you download a formerly welll-known app; someone downloaded the app, unzipped the executable (which is in zip format), resigned and uploaded. https://forum.xda-developers.com/t/app-quickpic-v4-5-2-class...