Silly question, but being unable to install 7zip from the notebook, and not having access to the underling system, I am here stuck with different 7zip archives obtained via wget which I am not able to extract.
Also I would like to avoid the obvious option of downloading archives locally, and eventually upload data unzipped or in different formats, not really a process I can automatize easily.
Not tested, but an idea:
DSX allows to install custom libraries. You could try to install py7zlib which is able to decompress 7zip archives:
!pip install --user py7zlib
An later something like
myfile=open(filename,"rb")
archive = py7zlib.Archive7z(myfile)
data = archive.getmember(archive.getnames()[0]).read()