If the issue is that you don't have Admin rights on your work or school PC, a portable version won't help anyway—the driver installation will always trigger a UAC popup asking for permission.
To understand why you can’t just drag-and-drop BlueStacks, look at what happens during a normal install: bluestacks portable download
Officially, BlueStacks does not offer a standalone "portable" version (like a .zip file you can run directly from a USB drive). The official BlueStacks website provides an installer that requires administrative privileges to set up virtual drivers on your PC. Why People Look for Portable Versions If the issue is that you don't have
For power users willing to edit scripts, here is a manual method that replicates of a portable experience using BlueStacks 5. This assumes you have admin rights on any PC you use, but want to avoid re-downloading games. Why People Look for Portable Versions For power