Need a Indie hackers slack channel?

In my entirely personal opinion, Absolutely not.

The best things about IH is that people share their stories and insight publicly, it's searchable through Google and shareable with just a link. If the discussion and advise is now behind a super secret (due to the fact that not every IH user will join it) inner group, moreover it's non searchable, non indexable, all older discussions are practically hidden. If that turns out to be the case I'd much rather go somewhere else.

Chat groups always become the echo chamber of the active 1% (that's an unrefined way of putting it, but you can see every other discord and slack group to see the truth in that). I'm against chat groups in massive communities because majority of users are lurkers who like to read rather than write. Chat mechanics work against it by flushing away everything apart from the ongoing discussion (sometimes even that). Yes, channels, threads and topics (a neat feature in Zulip) does mitigate it to some extent. That helps a group of 150 guys in a corporate office, not 45k people whose scale of activity is so massive, it's no better than WhatsApp or telegram styled chats.