I think Dash has a lot going for it despite not being cross-platform. I switch between nvim, xcode and pycharm throughout the day and like being able to look up a term without internet from any editor with a shortcut.
Dash is pretty essential to my development workflow. I’ve found using Dash through the Alfred integration combined with multiple monitors to be very productive.
While Dash isn't cross platform, there is Zeal https://zealdocs.org/ which works on Windows, Linux and macOS. It's very similar.