There are several different ways to edit Windows right-click context menus, from editing the registry using Regedit to options in several Windows utilities to single purpose apps like FileMenu Tools. You can find a brief review of FileMenu Tools & a few others here: techspot[.]com/guides/1670-windows-right-click-menu/
Of the apps listed in the TechSpot article, Easy Context menu is the only true portable app listed. The ZIP file includes both 32 & 64 bit versions, and while it appears to be rather old, dating to 2015, it has received updates to make it compatible with Win11.
The regular FileMenu Tools adds the program’s folder, a folder in ProgramData, and a recorded 532 new registry entries. There is an allegedly portable version available from the dev’s site, but it too adds the folder to ProgramData. That’s where the license data is stored, which includes a hardware ID, so it would need to be activated on every new piece of hardware, which may or may not be allowed. Using the Portable Apps format, register & unregister apps are included – registering the app in Windows registry, then removing that registration leaves nothing behind. The difference between the free & registered versions of the app are: Custom commands, plus unlimited number of files/folders. Free license only lets you use the context menu commands with up 20 files/folders.
TechSpot also lists the free CCLeaner portable… like FileMenu Tools it isn’t. The part that bothered me was running it used Explorer/Edge to silently contact the internet, though it also added 104 registry entries.