Hi! I haven't posted here before, but I'm a member of the Retool Power Users Slack and real-time events came up as a topic of conversation. I figured out how to do it a few months ago as a part of some consulting work, and I wrote a blog post about how it works.
https://www.thegoegetter.com/blog/real-time-retool
Shoutout to @justin for spurring me into action and helping me edit and shape this post!