An out of the box no TC or plugin solution is to make people select a single Topic for their Featured Topic, which is a core Discourse feature and do their updates there. This appears as a link on their user card. Supports one Topic only.
If you want something more complex to support multiple personal topics, in terms of open source work you could look at the ‘portfolio’ feature I wrote with the support of client funding in topic list previews plugin or Theme Component:
which allows a person to keep a set of special topics on their user profile. It places an additional route in User Activity. An additional ‘portfolio’ button on their user card takes you there for more easy discovery. These topics are distinguished with a site set tag or category. You can easily rename that feature from settings from ‘Portfolio’ to whatever you like.
Here’s an example in the wild: https://rideabl.es/u/scoota/activity/portfolio (currently filtered on ‘featured’. I renamed it Featured). This is currently in Tiles layout on desktop , but you can change that to look like a normal Topic List. It supports image previews on desktop as you can see. On mobile the view is a simpler, straightforward topic list.