The problem isn't that the vetted app store exists. It is that the vetted app store controlled by the device manufacturer is the only way you are allowed to install applications

My point being I knew that before I bought my iPhones/iPad. I actively like there being the one well kept store where things are verified and that apps can only be installed through. Granted not everyone will feel this way and I guess Android offers them more freedom in this respect.

iPhone users (like myself) need to look no further than the Mac to see what a better alternative might be. The Mac only allows App Store or signed apps to be installed by default. However this setting can be toggled to allow any apps for those who need that. You can also toggle it to allow only vetted App Store apps if that’s what you prefer.

Apple could keep the default to what it is on the iPhone right now, but should at least allow signed apps from other stores as a non-default option, even if they don’t allow unsigned apps at all.

And Android has done it that way from Day 1.

You might enjoy F-Droid then. All apps are built from source from public repositories, with known malicious libraries stripped, with a broad definition of "malicious" (tracking and advertising). Also everything's free, in both senses. No need to wall up the garden.