If you want that option, buy an Android phone.
The people who opt to buy IPhones for a premium price do so with the knowledge they want to buy their apps THROUGH the curated Apple App Store, not from some third-party malware infested app source. China had that with their side loading iPhone app stores. They were loaded with malware. Of the 10,000 or so hacked copies of commercial apps you could buy on the unofficial app stores a bargain prices, something like 4500 had malware and even Ransomware loaded in them! Thank you, we will pass!
Four of those actually got submitted by hackers masquerading as the developers and up loaded to the official Apple Chinese App Store and made it through the curation process before finally being caught by the real developers after being downloaded and getting their users’ devices infected. That is an example of why your idea is bad.
There is no reason to believe that a divested, independent app store(s) would have lower quality control. In fact, they would have maximum incentive to triple-check the apps against malware and spyware etc.