I like the pinephone and am going to buy one myself but I'm buying it because of linux reasons, not because I actually think it will be a good daily driver.
1. I did say it was usable, I am pretty sure most people could use it, although it wouldn't be a great pleasure (an personally I loathe these "addictive" mobile interfaces). One could get real work done with it.
2. I did say there was a gui for this. You don't have to type that if you don't want to. There are multiple gui front-ends with categories, descriptions, screenshots, ratings, etc. Courtesy of appstream metadata and packagekit, that both abstract away platform-specific package manager subtleties and provide "modern" store metadata.
3. This way a contrived example, there are simpler tools if all you want is record & play back.
4. "fun" is very subjective, that was part of my point.
Oh, and while we're on it, most distribution repositories are in fact walled gardens with a curated software selection (the audacity example above is part of it). That doesn't prevent you from sideloading whatever you want.