Plugin
@knodes/typedoc-plugin-pages
What would you want ?
Example repo: https://github.com/Hi-Fi/typedoc-plugins-example/tree/external_pages
When documentation is generated, external page can only be put at main level, not under "module" (which is actually namespace).

If trying to put page under module_2, it's not possible as it's not with moduleRoot as that produces error:
Error: Invalid pages configuration: could not find a workspace named "module_2"
And if just adding empty page, that would duplicate module_2 in list.