Scribus is a highly capable, free, and open-source desktop publishing application that stands as the premier alternative to InDesign. It is available for Windows, Mac, and Linux. Scribus supports professional features like CMYK color, spot colors, ICC color management, and the creation of PDF/X-1a and PDF/X-3 files, making it suitable for print-ready work. While it has a steeper learning curve, it is a powerful, safe, and cost-free tool for individuals and small publishers.

Even if you ignore the legal and security risks, the practical reality of using a portable version is fraught with problems:

Adobe desktop applications are deeply integrated into the host operating system. They rely heavily on shared system libraries, user fonts, hardware acceleration, and background licensing daemons. True "portable" versions of modern Adobe apps do not officially exist. Why People Search for InDesign CS6 Portable