This is the #1 legal alternative. Photopea (photopea.com) is a web app that opens and saves PSD files, supports layers, masks, blending options, and even runs most Photoshop shortcuts. It requires no installation or account. Save your work locally or to Google Drive.
A "portable" version of Photoshop CS6 is an unofficial, modified version of the software designed to run without a standard installation process. These versions are typically "portablized" by third parties to be loaded directly from a USB drive or a single folder on a hard drive. portableappzblogspotcom photoshop cs6 portable free
It runs smoothly on older hardware that might struggle with modern AI-heavy CC versions. Core Tools: This is the #1 legal alternative
: A dark-themed, redesigned user interface intended to keep the focus on the artwork. Save your work locally or to Google Drive
If you are simply experimenting on a virtual machine or an old laptop with no personal data, and you understand the risks, the "portableappz" blogs usually host the actual files. However, these files are often 10+ years old and will crash frequently on modern Windows builds.