CWC sell an XL sized NATO, only available in black, 340mm long. https://www.cwcwatch.com/collections...ng-watch-strap
Yellowdog Watchstraps do high quality leather and rubber straps - no nylon, they're custom sized and after you place an order you get an email asking you your wrist size. http://www.yellowdogwatchstraps.com/
I think the S-Series straps by Maratac are a touch longer than normal, the Nitrox17-Series definitely are. https://countycomm.com/collections/watch-bands