Since no official portable version exists, enthusiasts typically create these versions using "application virtualization" tools: Evolving from Office 2003 | Windows 11 Forum

The phrase "exclusive version" is a red flag. Exclusive software comes from Microsoft directly or a trusted vendor—not from a forum post promising "no password, fastest download." Preserve your digital safety. Leave Office 2003 in its well-earned retirement.

Legitimate alternatives to “portable Office”

However, the is worth pursuing. If you are a collector, a vintage PC gamer, or a writer who needs a distraction-free word processor, building your own portable copy (using the capture method above) is a rewarding weekend project.

A powerhouse for spreadsheets, famous for its snappy performance on low-end hardware.