Here's a video of my almost complete file to be used as a calendar picker in Pro or GO. Let's hope it works... The video, that is.
One script is needed in your parent file to perform the script in the calendar file. It waits until the user clicks the green button which returns the date(s) and this is grabbed using Get(ScriptResult).
The demo does this in my dashboard file and then finds the set of records for the returned date.