The interview was set up panel-style, but only a few participants spoke during it, so it seemed the other people were only there to listen in.
Overall, the interview itself was awkward: there was open disagreement between the parties about how the upcoming re-org was going to pan out in terms of the department positions/structure; a couple people said this wouldn't be a job, but a lifestyle; one person said they were not looking for people who need a job.
However, everyone was friendly and they seemed committed to finding a candidate who would be a good fit for the culture.
Based on the interview, I was no longer interested in the position. However, post-interview, I sent thank you messages and a follow up email, per standard business etiquette. I received a reply that they were conducting several other interviews and would be in touch. They never got in touch. From what I've read in other posts about TNG interviews, this is not unusual.