Yes, but they tend to burn down the house they're installed in. At least they used to. Haven't heard much about them lately.
Last I heard, they were recalled due to a fire hazard: United States Stove Company Recalls Pellet Stoves
Part of the issue was the venting was not the standard double wall PV. The new version is a wall mount with the standard 3” Flange for Pellet Vent. See pic US Stove 1,000 sq. ft. Wall-Mount Direct Vent Pellet Stove-4840 - The Home Depot
I originally liked the idea of just putting it in the window where the ac goes in the summer. The wall mount looks cool, nice and small, but you loose the portable option.
If you look around, you may be able to find a used one. However US Stove offered money towards a wall mount to owners of recalled units. In order to get the money they had to send in the main control board of the window mount pellet stove to assure the stove was disabled.