Report
Indie Hacker is an obvious crowd favorite for launching an Indie business, then there's Hacker News, and Product Hunt , there's BetaList. What else?
Twitter for sure! connects everything else.
Twitter is fantastic, but there's no official "launch" feature. On the other hand, I could launch the same product every day for a week, and probably not annoy too many people that way.
Some numbers from https://versoly.com/ last 30 days
I launched on Betalist and Product Hunt.
PH - 1750
IH - 575
Betalist - 466
Stackshare - 232
https://startupresources.io/ by @pauldmet - 62
Your own platform - ie the personal audience you have built (or should be building)
Reddit is a good place to launch too.