While it wouldn’t be in the preview mode exactly, the Templater Plugin has a System module with a prompt and suggested function that can do just what you’re after.
Mood today: <% tp.system.suggester(["Happy", "Sad", "Confused"], ["Happy", "Sad", "Confused"]) %>
The first array is the available options that are displayed. The 2nd array is the actual values for what is displayed; this means that if you select Happy, then Happy should be written out.