Our take on the ranking
Short answer: for a thermal that lives in a jacket pocket, the TOPDON TS004 Pro ($899) comes first by a hair: 310 g, a 384 sensor and up to 10 hours of battery. The Pulsar Axion XQ19 (249 g, widest view) and the RIX Pocket K3 (213 g, 5-year warranty) score the same 9.1, so pick on view or warranty. If you need more reach in a small body, the Pulsar Axion 2 LRF XG35 packs a 640 sensor and a rangefinder into 350 g.
A compact thermal gets used. It rides in a chest pocket on the walk to the stand, comes out at every noise and goes back in without a thought. So here, grams and battery hours come first, and the sensor, reach and price come after.
Ten models weigh 450 g (about 1 lb) or less with a battery. At the top, the TS004 Pro, the Axion XQ19 and the RIX K3 are separated by a hair. They suit different people: the XQ19 for wide, fast scanning in timber, the K3 for the lightest body and the longest warranty, the TS004 Pro for the longest battery and a 19 mm lens.
Pocket size has a price in reach. The 15 to 19 mm lenses of the small models detect a person at roughly 670 to 950 m. If you want the same pocket feel with twice the reach, the Axion 2 XG35 and Axion 2 LRF XG35 are the ones, at two to three times the price.
Scope: handheld monoculars that weigh 450 g (about 1 lb) or less with a battery, the ones that live in a jacket pocket. Scores on this page use the carry score weights (weight (with battery) 35%, sensor resolution 15%, battery life 15%, price 15%, reach (lens / pixel pitch) 10%, thermal sensitivity (netd) 5%, water protection 5%); each review shows the overall score.