User blog comment:MisterWoodhouse/The Unified Community Platform Editor and our first release date/@comment-45835827-20200524153434/@comment-37336800-20200524160744

Polls, Blogs, and Article Comments have yet to be added to UCP (And Polls and Blogs may not end up existing, though I have hope).

Message Walls, The Europa Infobox Theme, and "Require all contributors to log in" all exist.

New Image Galleries seems to have halted development around 2015-2017, and chat isn't on UCP atm and may not end up existing as it doesn't seem to have received any updates since at least 2017. Though I imagine chat will show up eventually given it's popularity