Websockets to me don't seem like the ideal approach here, since the communication is just from the server to the client (an update of a data payload once an event occurs in the backend system).
Websockets have quite a bit of technical complexity requiring significant architectural effort to ensure reliability of a service. Ably is a company that offers websockets as a service and has some good blog articles to start you out if you're sure about this path.
What I would recommend with the details provided so far is to either use SSE or long-polling. The "downsides" are often over-exaggerated, and there are lots of businesses that one would assume use websockets that really are just using SSEs because operationally and architecturally it is vastly simpler to reason about.
I can almost guarantee that the complexity of adding another API endpoint will be drastically less than standing up a reliable websocket infrastructure.
