I originally wrote a long post about different methods but realized no one here has tried them because they all claim (understandably) to take years to work.
Instead I'll ask a different question: has anyone here tried sungazing? Years ago I would watch a youtuber named sv3rige and he really swore by sungazing, said it was practiced by "the ancients" and has all these health benefits. Well I know certain people have also claimed it improves vision. Probably a long shot but I figured I'd ask anyway.
There is also something called the "no BS guide to vision improvement" (https://losetheglasses.org/cliffgnu-vision.pdf) but it reads like a copypasta. It's attractive because the author is an IT professional who claims to have gone from "worse-than 20/200 to better-than 20/40"