alt Hacker NewsZulip used to have a really neat feature where you could open up certain channels to be indexable by search engines. Basically turning it into an open forum. The feature is still sorta around but completely broken. Quite unfortunate imo. It was a really neat solution to the walled garden problem with team chats
Zulip product lead here -- I'm not aware of anything in this space that used to work and no longer does.
There's long been a way to make Zulip channels searchable with zulip-archive (https://github.com/zulip/zulip-archive), and that continues to be available.
Making the app-native web-public channels accessible to search engines is a big technical project, tracked as https://github.com/zulip/zulip/issues/21881.