This is the closest thing to a true "portable" solution. Microsoft offers free, browser-based versions of Word, Excel, PowerPoint, and OneDrive. You can access them from any computer with an internet connection and a modern web browser, with no installation required at all. While they lack some advanced features of the desktop apps, they are perfectly capable for most everyday tasks and are completely secure.
Running the latest suite on older hardware or specialized, air-gapped computers. How to Properly Use Office on the Go (Safer Alternatives) microsoft office ltsc pro plus 2021 portable