It doesn't modify the Windows Registry.
Since these versions are unofficial, they do not receive critical security patches . Using an unpatched version of Word exposes you to vulnerabilities where simply opening a document can lead to a system compromise. Microsoft Office Word Portable Download
The closest official "portable" experience is Microsoft 365 Online , which is free and runs in any web browser. It doesn't modify the Windows Registry
You won't receive critical security patches, leaving your documents vulnerable. ⚖️ Licensing Issues browser-based) or Office 365 (paid
Microsoft does offer (free, browser-based) or Office 365 (paid, installed normally). No portable version exists from Microsoft directly.