Great post! I think you’re certainly on the right track.
Personally, in sites created recently I’ve put intro and all icebreaker topics in a “water cooler” category, where others can then also start more topics as they see fit that don’t fit in anywhere else and are intended to strengthen ties in the community or for blowing off some steam. There’s also a water cooler chat.
I also created an automation to add a badge when someone has responded to the introductions topic, and to remind new members a couple times to respond to it if they have not done so. The same could be nice for icebreaker topics.
