There are several ways to approach a launcher. The most common is to create a table where each row describes a particular launcher (its name and a button image, at least), and a gallery view atop that table to display the list of launchers. The view itself would be configured with a row-selected event that determines which launcher was chosen and what to do.
How to trigger the correct action given you can only trigger one action: The one action should be of type Grouped: execute a sequence of actions. Populate that action with all the actions your launcher can do. Set the Only if this condition is true expression to only be TRUE for the intended action.