We’d also really like a feature where joining a group auto-subs you to a chat as well. The current option to auto-subscribe anyone with access to a category is basically useless for us. It auto-subscribes everyone as most of the categories are open to anyone.
We can’t know a priori who wants to participate except by them joining groups. So this would be our preferred option: add something to the group configuration to auto-subscribe to channel(s), in a similar way we can configure to watch categories and tags.