The main thing, axial length reduction through undercorrection, has been shown in plenty of animals and humans.
I understand there’s an industry that wants to be paid for prescription glasses and lenses and whatnot, and that can throw a wrench and it does into the whole thing - see the Sugar vs Fat vs Whatever industry battle. But a little would go a long way.
https://iovs.arvojournals.org/article.aspx?articleid=2772368
https://iovs.arvojournals.org/article.aspx?articleid=2126435
https://journals.plos.org/plosone/article?id=10.1371%2Fjourn...
"In addition, in myopes, calculated defocus caused longer eyes (+8.4 ± 9.0 µm, P = 0.001). Strikingly, myopic eyes became also longer with positive defocus (+9.1 ± 11.2 µm, P = 0.02)."