[rst]

FWIW, some of the hosted Slack alternatives, like Zulip, support at least versions of some of these -- see their integrations page here: https://zulip.com/integrations/

What would be ideal from this perspective would be if they could make the integrations somehow code-compatible with Slack, but that's tough. For example, Zulip's topic system is, IMHO, vastly superior to Slack's threads, but every public message is under some topic (within a stream -- there are two levels, not one), everything posting a public message has to supply one, and that alone might make it difficult to reuse a Slack integration unaltered.