Your eye's axial elongation is caused by the eye growing longer, which means *more cells in the eye.* Your eye grows in response to visual stimulus, without the brain's involvement. Your eye shape physically changes by *extra cell production* to cause axial elongation. This process is called emmetropization. It's extremely well understood. Peripheral defocus lenses and low dose atropine are proven to work in reducing speed of myopia progression because they reduce the stimulus causing the eye to elongate. Let me say that again: The way axial elongation happens is well understood, and we have known interventions to interfere with the growth stimulus. We know how to control myopia.
There is no known way to reverse this growth process. The only scientifically proven intervention for reducing myopia is surgery. There is no concrete evidence of for any other intervention, nor is there any other known mechanism for causing the eye to reshape itself to reduce axial elongation. For the eye to become truly less elongated, your body has to break down the extra cells in the eye and cause reshaping. An example of this is wound healing: your body breaks down the ECM with TMP activation. We know how the *opposite* works, the eye grows in response to overfocus to find focus. When too much is in focus in your peripheral vision (near work, holding things close to your face), the eye thinks it's over-focusing, and physically grows to find focus. Near work is the issue. Outdoor light probably isn't the issue, it's probably because when you're outside, you're not doing near work.
For those who do experience improvements, it's not from changes to the cellular structure of the eye. There are multiple temporary known mechanisms for your eye changing focus. One of them is the thickness of the choroid, a tissue layer in the back of the eye. Another is possibly muscular, your axial elongation is known to show variable diopters during the day (maybe +-0.25 but I don't know the actual variance). Studies do show fast-acting axial elongation reduction (minutes to hours) in response to defocus, but this is obviously not from the eye reshaping itself, so this is obviously not reversing myopia, this is just changing temporary variables in the eye. For the majority of people who report "reversing" myopia, it is usually a negligible change (2 diopters) which is easily explainable with these mechanisms, rather than the false belief it's actually changing the elongated eye shape. Ortho-K is another known temporary / superficial intervention.
The burden of proof of truly changing the axial elongation and fundamental structure of the eye cells is on you, and on the EndMyopia quacks. There are no studies that demonstrate significant diopter changes that would demonstrate the eye is reshaping itself to actually reverse myopia. You are welcome to find the studies on the Bates method and wearing undercorrected lenses yourself, they don't work and possibly make things worse.