Everybody can do that themselves, if the original maintainers don't want to (which is a security problem ;):

   If you are not the author, we suggest you first reach out to the author with an issue in their GitHub repo to request that they publish their extension to open-vsx.org. We've drafted a template with suggested content for the issue.

https://github.com/eclipse/openvsx/wiki/Publishing-Extension...

Such "3rd party extensions" don't get the "verified publisher" icon (or at least should not get it ;).

Encourage you to look at the bigger picture. What happens when there’s an official extension by a 3rd party vendor SDK that defines a dependency on the proprietary language server/extension. It’ll work fine for “Visual Studio Code” but all these OSS forks (inc recent venture capital funding for AI ones) gets wrecked. It turns into a game of having to iterate through the graph and trying to convince official SDKs to change their product direction.