> Google was a bit smarter about avoiding potential anti-trust though, because they at least give the illusion of choice with 3rd party app stores.
I'd argue the opposite -- one of Epic's allegations is that Google scuttled a deal Epic had reached with OnePlus to ship Epic's own Android app store.
The illusion of choice has nothing to do with what is the default choice.
The choice is important. About 20% of apps on my Android phone come from F-Droid marketplace distributing free software and some of them are not distributed via Play store at all. And then there are Amazon App Store, Galaxy Store etc. (device-manufacturer stores) https://fossbytes.com/10-google-play-store-alternatives/
There basically is not a competitive market for either app marketplace right now, so an accurate price can't be determined. Allow 3rd party marketplaces to be installed as easily as any other app and I'm certain prices will come down from where they are today.