We have been using Gitter.im for our "official" chat since 2015, when there was interest in adopting Slack instead of continuing to use IRC. The issues around IRC were: quickly dropping users, no visibility among younger developers, difficulty reaching people who asked questions but disconnected, and so on.
For various reasons, which you can find by searching through the archives of this forum but primarily the question of openness, we settled on Gitter, and it was added to Plone.org (the sidecar chat, and community documentation around chat and support).
In 2020 we ran the Plone conference using LoudSwarm.com, which combines Zoom and Slack to make it easy to attend and participate in online events. The Volto team has been using a channel in that Slack, otherwise that Slack (plone.slack.com) has remained primarily for some to use for direct messages and some teams such as the AI (admin and infrastructure), marketing, and possibly others.
For a while, @jean and I had set up https://sameroom.io to bridge between IRC, Slack, and Gitter, but the service had changed hands and seemed to have stopped working a while ago. It seems to be available still, so perhaps we could try to set it up again, but it was always intended as a temporary measure until the Plone community had settled on one "official" chat service.
Now we no longer discuss IRC, not really
We really do try to point newcomers and questions to this forum, where it's easy to search and locate past answers, and we prefer this forum to Stack Overflow, where most of us do not actively spend time looking for Plone questions to answer.
So, long story short, is it time to revisit the above arrangements?
Our primary concerns have to be:
maintaining the visibility of Plone activity, and by "Plone" I mean all the subprojects: Plone, Zope, Volto, Guillotina. Keeping our activity behind a semi-private wall is not a good idea.
We also need to concentrate our activity as much as possible in one place, otherwise we will be spread too thinly.