Is there a library in Python which allows virtual file system management in single file?

I was working on a program. I do not think I need to show it here, but I was wondering is it possible to create virtual file system stored on a single file. for example I have a file named my_file_system.fs, is there a way to create virtual file system into that single file only. Basically:

/home/xcodz/
    |
    +--myfilesystem.fs
       |
       +--testdir
       +--test.txt
       +--downloads
          |
          +--example1.txt

I basically want basic filesystem interface. no owners, date or other metadata. Zip is a good idea to do that but it just reads the whole file in the system all at once and does not provide file like interface. So I rquired a very basic file system in single file, in which i am able to use files like normal IO objects.

EDIT The files stored in the file system will be as big as 3 GB for a single file, and I do not have that much of a ram. TarFiles doesn't seem to make my work any better

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