I’m not sure I understand the problem. Are you trying to connect to a websocket endpoint with the above pattern? Is there a reason you can’t connect directly to the url with the uuid?
You can do it but you’d have to make your own websocket override module, it is actually very easy to do and involves mostly copying the existing module.
The entire ‘socket’ system in Phoenix is pluggable, you could even design a new one that, oh, goes over SCTP or some proprietary protocol or whatever you want. In this case a simple edit to the websocket to handle it differently. It just comes with WebSocket and LongPolling as transports by default (which you choose in your socket setup file via transport).