Make tart shell: Coarsely chop pecans and salt in a food processor. Add dates; pulse until thoroughly combined, 15 to 20 seconds. Add syrup; pulse just until combined and mixture sticks together. Press nut mixture firmly and evenly into a 9-inch pie plate, wetting your fingers as needed. Set tart shell aside.

Make filling: Grind nuts to a coarse paste in a blender. Add water, syrup, and vanilla scrapings; blend until smooth, about 5 minutes, scraping sides as needed. Mixture should be the consistency of thick pancake batter. Set aside 2 Tbsp coconut; add remainder to blender, and process to combine. Pour into prepared shell, spreading evenly.

Thinly slice bananas on the bias. Sprinkle with reserved coconut; serve immediately.