Thanks. It'll become a card-based GUI eventually.
Visually it's all in the Unity UI, each line logged to the console is its own Text object. The console is a scroll view containing a vertical layout group and a content size fitter that aligns the newer text items at the bottom.
The text prompt is its own object with an Input Field outside the scroll view, with an event handler on End Edit that calls a script I wrote to parse the command and log it to the output.