The closest substitute I've seen to portable python is https://winpython.github.io/
But awhile back they dropped support for Python 2.
So not all that useful unless you're willing to make the jump to supporting multiple python versions.
Some other options would be converting the python tool into an exe, an then distributing that.
There are multiple tools that try to fill that void,
PyInstaller, cx_freeze, and Py2exe, being the 3 that I know about.
None of these options will work if you need to reference Maya specific libraries as part of the tool. Those would need to be run through
mayapy.exe or in an instance of Maya it self.