There is or installer for Autodesk Fusion . The software must be installed on a local drive as it requires specific system and user-profile subfolders to function.

While not strictly portable, Autodesk provides an "Admin Install" or offline installer for environments with limited internet or specific deployment needs.

Sometimes, late at night, Alex still sees the search suggestion pop up: "fusion 360 portable download install"

In short:

After three days of data recovery and a humiliating call to the client, Alex learned the hard truth: