As Drupal is a "server-generated" fronted, question: should the server keep the wss to relays open, subs REQs, send&sign events or should that be done by the js client in the browser?
Discussion
Could be both, depends on what you're trying to accomplish. There are clients which are using server-side websocket connections (I've to look this up tbh) but most connections are handles by JS (which is preferable).