Due to requiring multiple sensors and lenses, 360 cameras usually feature small to medium-sized sensors. While smaller sensors do not perform as well in low light conditions, they allow camera designers to build smaller rigs with the lenses and sensors closer together. This minimizes parallax and can help to make the stitching process easier.
As an example, one of the larger off-the-shelf professional 3D-360 cameras has ten Micro 4/3rds (MFT) sensors and fisheye lenses; image quality is excellent, but due to the large distance between lenses and sensors, it is challenging to stitch comfortable 3D-360 video when there are close subjects, and output is not human scale when viewed in VR headsets. The camera is also extremely large, making it difficult to fit into smaller physical spaces.
Other cameras use 6 to 8 lenses, some with smaller sensors. These allow for closer subject distances, can capture closer-to-human-scale stereoscopic video, and they are compact enough to fit into smaller physical spaces.
Finally, at the smallest end of the spectrum, dual lens cameras with 1-inch-type or smaller sensors are pocketable, capture monoscopic 360 video, and can fit into very compact spaces such as car interiors.They are commonly used as POV / action cameras to capture sports.
Although smaller sensors yield smaller cameras, they capture noisier video than larger sensors do, and have a smaller dynamic range (this can be challenging when shooting indoor scenes with bright windows, for example).