- The underlying python code cannot use open() to access its own resources, but must use pkg_resources, and most packages on pypi don't do that because most dev don't even know it exists or what problem is soves.
- _ _ file _ _ is not available, breaking a lot of things. zip_safe is a build option, but actual compliance to it is hard work and rare.
I was thinking more along the lines of using namespaces and FUSE. I'm aware that Python kinda treats them like folders transparently, but not completely for reasons (and more) that you described.
A 2016 comparison by the developer of WinFsp says WinFsp is several times faster in performance tests [1]. According to the readme for Donaky [2], since then Dokany got faster.