Is it possible to run NGINX as a reverse proxy connected to Argo and have CNAME DNS entries pointing to the root so that specific sub domains will hit the Argo tunnel, and NGINX can route the subdomain that was requested to the proper port that the service is running on? For example, NGINX reverse proxy running on http://example.com. DNS CNAME entry of subdomain1, and NGINX has an entry for subdomain1 to route to http://localhost:3000.
Would it be possible for you to clarify what you trying to achieve here?
Is there a specific point of having nginx as a reverse proxy here?
You can find more details about Argo Tunnel here: