This component is not yet implemented in Thunkable X. In the project below, on the Pickers screen, there is an example of creating a custom listpickers.
i feel more difficult than appinventor for android.
This means that when you click on the button, you will go to the scrListPicker screen.
You are right, it is unusual to work with Thunkable X first, but try to work a little with it and you will see that some things are done in it conveniently.
Just a note that you can use the List Viewer component to enable the user to select an item from a list. It’s not the same as a List Picker but it allows for similar functionality.
Here is a very simple sample app that I created to demonstrate: https://x.thunkable.com/copy/184beae0ea5adb841d4fc5b35d3703c4