Coat a 9-inch square baking pan with cooking spray. Line with parchment paper, leaving a 1-inch overhang on 2 sides. Lightly coat parchment with cooking spray.

Stir together walnuts, cashews, pistachios, apricots, mango, cherries, and coconut (if using) in a large bowl. Remove ¼ cup mixture; reserve for topping. 

Process dates, nut butter, salt, and 1 tablespoon hot water in a food processor until a smooth paste forms, 1 to 2 minutes. Transfer to bowl with nut mixture; stir and knead until well combined.

Transfer mixture to prepared baking pan and press firmly into an even layer. Scatter reserved 1/4 cup nut-and-fruit mixture on top, pressing to adhere. Cover and refrigerate until firm, about 2 hours. (Or freeze until firm, about 30 minutes.)

Using parchment paper as handles, lift from baking pan and transfer to a cutting board. Slice into bars.