Dynamic websocket URL?

I'm trying to set up a websocket connection to the Sense energy monitor API. The URL takes the form wss://clientrt.sense.com/monitors/%s/realtimefeed?access_token=%s, and thus is somewhat dynamic. I have a login flow that sets the monitor ID and access token in the flow's context, but I don't see a way to get at those values to create the URL for the websocket client config.

Is there any way to do this?

UPDATE: Can I use {{ }} in any node property field? Maybe something like wss://clientrt.sense.com/monitors/{{ global.get("monitorID") }}/realtimefeed?

UPDATE 2:

After some experimentation, I found I can put {{ msg.payload }} in a Dashboard Text node value, but not {{ global.senseRealtime.payload.w }}. But I can use senseRealtime.payload.w as part of a global. inject node assignment.