[etlandis]

Well you'd have to download them, but

Mac: Dash (https://kapeli.com/dash)

Mac/Linux/Windows: Zeal (https://zealdocs.org/)

Windows: Velocity (https://velocity.silverlakesoftware.com/)

all support a healthy amount of documentation that you can download and most importantly a very healthy amount of integrations from Vim (https://github.com/KabbAmine/zeavim.vim) to VSCode (https://github.com/deerawan/vscode-dash) - note that on Windows all these apps write to the registry as "Zeal" so remember to uninstall the previous one if you're switching between them and using an integration.

If you just need a searchable docset that can be made available offline, there's also DevDocs (https://devdocs.io/) - just note that downloaded documentation can disappear if you regularly use the same browser for normal internet use - I'd do things like grab a copy of ungoogled chromium and just use it for this site before traveling if you're gonna be offline for a while (alternatively, there's some electron versions out there and you could package it that way for yourself too)