Good philosophy!
> Every application comes in its own directory that can easily be “managed” using the file manager, no need for package managers
Didn't catch just how it works, but makes me think of GoboLinux [1]. (Oh, there's a 2020 release of GoboLinux.) Is it not a bad idea to use .app when macOS already does? Perhaps .program would fit. Or could they be compatible so one .app runs on both operating systems?