Is there such a thing? Maybe a website and/or forum?
Not looking for a source on "how to be funny" kind of thing.
More like practical advice - good venues, bad venues, agents, pay rates, travel advice, stuff like that.
I'm thinking about actual standup rather than comedy magic.

Hey cheese, although I can think of a couple of Comedy forums, none of them are business related.

If you are looking for information on that stuff your best bet would be the trick business forum down below.
https://themagiccafe.com/forums/viewforum.php?forum=44&88331

There's a couple of folks who post there with experience in Comedy clubs, also there is existing info about agents
and the like, it probably won't matter that you don't perform magic.

Thanks Fedora!