Single 26650 flashlights
Although there are tons of 18650 sizes flashlights, there aren't many 26650 sized ones. Below I will try to add some reviews that are powered by 26650 batteries.
A great budget performer, that is able to blast 2400 lumens and almost 200KCD.
Astrolux MF01 Mini
5,500 / 6,300 Lumens with a single 26650 battery. Great pocket rocket.
DQG Tiny II
Lovely little light powering 1200 lumens. Blast from the past
Very bright flashlight sporting a XHP70.2 LED.