Since Microsoft doesn’t provide this, how do third-party repackagers create a Microsoft Office LTSC Pro Plus 2021 Portable?

Office relies on robust registry entries to save user preferences and document recovery data. In a portable environment, these writes are often redirected or fail silently.

Standard Office 2021 requires installation, registry entries, and activation servers. LTSC is often preferred by power users because it is leaner and avoids the bloat of the Microsoft 365 updater.