Search for the desired context under HKEY_CLASSES_ROOT. For commands that trigger on:

• A specific file extension -> specific key, e.g. .py
• All files -> *
• Directories -> Directory

+-- {{ CONTEXT }}
    +-- shell
        +-- {{ KEY }}: {
            |   (Default): REG_SZ = {{ NAME }}
            |   Icon: REG_SZ = {{ ICONPATH }}
            | }
            +-- command: {
                    (Default): REG_SZ = {{ COMMAND }}
                  }

Right-click

https://stackoverflow.com/questions/6440715/how-to-pass-multiple-filenames-to-a-context-menu-shell-command

https://superuser.com/questions/569466/add-a-directory-and-all-subdirectories-to-the-path-variable-with-a-single-entry

https://docs.microsoft.com/en-us/windows/win32/shell/how-to-employ-the-verb-selection-model

https://stackoverflow.com/questions/6440715/how-to-pass-multiple-filenames-to-a-context-menu-shell-command

https://stackoverflow.com/questions/27088510/implement-explorer-contextmenu-and-pass-multiple-files-to-one-program-instance