@reiver@atomicpoet Here are some ideas:
Technical topics - you have ideas already I'm sure. Scaling, responding to DDOS, spam control, etc.
Moderation. From the moderator's POV and from the user's. Arguments around pre-blocking, blocklist management, pros and cons. Proactive vs reactive. This is a more complex topic than some like to think.
Talk about particular instances and news related to them. Fosstodon goes invite-only. Talk to some of their users and admins about what they have seen and want to see in the future. Do a survey of the Star Trek instances.
Hashtaggery. What's up with Mosstodon? How about CasioCult? Highlight some of the interesting inter-instance communities. Dadjokes is pretty active!
Personalities. Journalists. The passing and legacy of Kris Nova. mekka okereke. Veronica Explains. Grammar Girl. Technology Connections. Admins like stux or Jerry.
The Infosec community. Jerry has an absolute armada of Fediverse servers.
Orgs and companies on the Fediverse. What kind of impact are they having and seeing? Talk to their social managers about how the Fed is like or different from others. Talk to their followers and blockers.
Comedy on the Fediverse. Low Quality Facts. Dadjokes hashtag. RikerGoogling.
Migrating instances. Who's done it and why? How to make it go well? How to make it go poorly? What's the user experience like after migration?
The Reddit to Lemmy/Kbin migration.
The X-twitter to Mastodon migration.
How about the other biggies, like Facebook or Instagram or Linkedin?
Running an instance. How to get started? How to fund it? Why would you want to? Why would you not want to? Talk to Jerry. Talk to Amin Hollon. Talk to someone who runs a single-user instance.
So many possibilities. Lots more I haven't mentioned.