I'm going to be there and generally hacking on API stuff (likely with a focus on unblocking T92893: Update ApiSandbox to MediaWiki appearance using OOjs UI if oojs-ui devs aren't too busy to work with me), and I'd welcome people just coming up and asking me about API stuff. But it might be useful to have a spot on the schedule to chat about it as a group.
No presentation, and not a training session. Just whatever people might want to talk about regarding pain points in using the API (as a MediaWiki developer or as an end user) and ideas to improve it.