There are potentially multiple proxies involved with jupyterhub:
- the jupyterhub proxy between jupyterhub and the singleuser servers: jupyterhub dynamically updates the routes whenever singleuser servers are started/stopped
- an optional web proxy between jupyterhub/other apps and the internet.
The brief mention of caddy is the latter, so your easiest option is to treat OMERO and jupyterhub (including the JupyterHub proxy) as backend services, and use Caddy as your front-end.
I don’t know whether it’s possible to add routes to the JupyterHub Traefik proxy.