While not a portable version provider itself, Slimjet hosts a large archive of official Chrome offline installers for Windows, Linux, and Mac that can be manually converted into portable formats. Step-by-Step Installation Guide
Safer alternatives
: Provides older versions of Chromium-based browsers, often useful when looking for specific major version rollbacks. How to Set It Up Safely Older versions of Google Chrome Portable (Windows) google chrome portable old version
Because Google only provides the latest stable release, you must rely on community-maintained archives. While not a portable version provider itself, Slimjet