Server-Sent Events are under-appreciated. I get that people are scared of them because each ties up one of six connections (browser-wide) to the domain. But that's only under http 1.1. Under http/2 you get 100 usually. So no biggie?
The advantages are: amazingly simple API. You can have something useful, with automatic reconnects, in a few lines of JS. #WebSockets almost always involve loading a 3rd party library to take care of all the tricky bits.
Using server-sent events - Web APIs | MDN
Developing a web application that uses server-sent events is straightforward. You'll need a bit of code on the server to stream events to the front-end, but the client side code works almost identically to websockets in part of handling incoming events. This is a one-way connection, so you can't send events from a client to a server.
MDN Web Docs (developer.mozilla.org)