For the crust: Preheat the oven to 350 degrees F. Stir together the graham cracker crumbs, sugar and melted butter in a medium bowl until combined. Use the bottom of a measuring cup to press the crumbs firmly into the bottom and up the sides of a 9-inch pie plate. Bake until the crumbs have toasted and set, 8 to 10 minutes. Transfer to a wire rack and let cool completely.
For the filling and graham cracker layer: Puree the cream cheese and sweetened condensed milk in a food processor until silky and completely smooth, scraping down the sides of the bowl with a rubber spatula as needed. Add the citrus zest, juice and salt, then pulse until combined.
Pour half of the filling into the cooled cookie crust, then sprinkle with the chopped graham crackers. Top with the remaining filling, then smooth out the top into an even layer with an offset spatula. Refrigerate until chilled through and set, at least 4 hours but preferably overnight.
For the whipped cream topping: Whisk together the heavy cream and confectioners' sugar in a large bowl until stiff peaks form. Transfer to a piping bag fitted with a star tip. Pipe large star-shaped dollops of whipped cream around the edge of the pie, then decorate with lime and lemon rounds—you can cut slits in them first then twist the rounds, if desired. Cut the pie wedges and serve chilled.