While not truly "portable," some users have explored methods to carry Fusion 360 on a portable drive:
However, note that performance might be affected, and compatibility issues could arise depending on the host computer's configuration. autodesk+fusion+360+portable+install
Fusion 360 uses a "streaming" installer. This means the initial download is small, and the rest of the data downloads in the background while you work. While not truly "portable," some users have explored
If you truly need CAD portability without installing anything on host computers, abandon the "portable install" dream and consider a cloud-hosted virtual desktop. However, note that performance might be affected, and