Some reading for the interested. Is it sensor size that is the MAIN factor in producing noise. Not directly. Is it pixel size? Nope. It is amount of light gathered by the lens's entrance pupil that is the main factor in producing noise, at least according to the Clarkvision website, which has many great articles on the subject, including this one:
https://clarkvision.com/articles/does.pixel.size.matter2/
Some excerpts from various articles on that site:
"The true differences in apparent noise are due to the amount of light collected by each camera. The common internet cited reason for the larger sensor camera is that the sensor is responsible. No, it is the lens. The sensor is just a receptacle to hold the photoelectrons. The analogy is a water bucket: the reason for the amount of water in the bucket is how fast and for how long you poured water in the bucket. The size of the bucket only determines when/if the water will fill and overflow the bucket. Another cited reason for the difference in noise is the larger pixels need more light to fill the pixel. That is a consequence of large pixels, not a reason for noise. Noise is the square root of the number pf photons (photoelectrons in the pixel), and that is independent of how full the pixel is."
"Larger sensors
enable one to use larger physical aperture lenses. For example, say you have a 35 mm f/1.4 lens and a 1.6x crop sensor camera. The lens covers the field of view you require. Upgrading to a full frame sensor and 50 mm f/1.4 lens would provide 2x additional light collected from the subject, so a 1-stop improvement,
due to the larger lens."
"There are three factors that determine the
true exposure in a camera +lens. 1) The lens area, or more accurately, the lens entrance pupil, which is the effective light collection area of a complex lens. The area determines how much light the lens collects to deliver to the sensor. 2) The angular area of the
subject. The product of these two values is called Etendue, or A*Ω (A*Omega) product. (A= the lens entrance pupil area, and Ω, omega = the angular area of subject). The third value is 3) exposure time, the length of time the sensor is exposed to light. One way to think of this is the lens area collects the light, the focal length of the lens spreads out the light and the pixels collect the light spread out by the lens. While a larger pixel collects more light than a smaller pixel, which led to the concept that larger sensors are more sensitive (which is not strictly true), the subject at the sensor is still the same angular size, thus independent of pixels. Changing pixel size simply trades spatial resolution (pixels on subject) for more light per pixel, but does not change the same total light from the subject. Only changing the lens collection area changes the total light collected (or moving closer with the same lens so the inverse square law comes into effect)."
"When then lens aperture diameters are the same and the pixels on the subject in the output presentation are the same and the exposure times are the same, then the images from different cameras will show the same depth of field, and the same signal-to-noise ratio regardless of sensor size."