Yep, you can use assign here, and the assignee(s) will show up on the cards. Note that you can assign posts within a topic in addition to assigning the topic as a whole to a person.
This is not something we have in there yet. Probably need to dive a bit more into what you’re thinking here in a Contribute > Feature topic.
Posts in topics are a good start. Changing tags / moving columns would be next. We do log some activity like this, so tinkering with what you can and cannot extract via Data Explorer may be informative.
I do have some hopes and dreams when it comes to this space myself – I’d love to have two things: 1) a kind of board wide “activity stream”, and 2) board history stored as snapshots of the board state.
(1) is something I think many products do already, so should feel familiar if we do it.
(2) is not something I’ve seen before, but I feel like it’s within reach and could be quite powerful. I’m imagining it opening the door to two things: a) having permalinks to a given board state (e.g. for linking to “current state” in a periodic updates from a topic), and b) having something like a “scrubbable timeline” where you could see how the board has changed over time.
Not sure (2) will happen before other things become more important, but it’s something I’m keen to explore if we can make space for it.