Which exchanges actually offer a WebSocket stream for announcements?

I've been collecting exchange announcements for a while and I keep running into the same wall: almost everyone expects you to poll an HTML page or a support-article endpoint.

Two exceptions I've found so far. Binance and Gate.io both let you subscribe to announcements over their own WebSocket streams, so there is no polling interval to sit through and no cache layer in between. Everything else I watch gets polled at high frequency.

Has anyone found others? Specifically looking for three things.

An official WebSocket or SSE endpoint for announcements, not for market data. Plenty of exchanges stream trades and order books; almost none stream announcements.

Anything on the Korean exchanges. Upbit and Bithumb publish listings that move markets and I would love to stop polling them.

Webhook-style push, if any exchange offers it at all.

Happy to share what I learned about the ones I've already wired up, including the parts that surprised me about how announcement timestamps behave.