You don't need to jailbreak it. Swipe from the top and press the big button labelled "dark mode".
It is a somewhat newish feature, I think pre-2020 models don't have dark mode, afaik (and I have no idea how are old devices supported on kindle, I assume launch and forget, could be wrong though).
alt Hacker News
It is a somewhat newish feature, I think pre-2020 models don't have dark mode, afaik (and I have no idea how are old devices supported on kindle, I assume launch and forget, could be wrong though).