People used to do this at tech conferences, but using Twitter. Someone would start a hashtag and people would jump in. There was always a fun side-channel going with people commenting on what was being presented on the main stage.
Fun times, before… sigh
Programming.dev seems like a good option.
Since this is meta… however this ends up getting resolved could be a good template for consolidating multiple sparse communities across the Fediverse into a single, more populated one.