There is already open source dash (https://zealdocs.or) although they don't provide Mac build because of an agreement to use some of dash's lists.

But you can build it on mac (https://github.com/zealdocs/zeal/wiki/Build-Instructions-for...)

I've been missing Dash so much since I moved back to Linux, on my todo list is to create a Web based clone, that supports custom packages which was Dash's killer feature. And with top class Emacs integration, instead of having to context switch to a browser.

Currently focused on launching another project and I will have to get back to it, my productivity has tanked now that I constantly need to have a browser tab or three open on hexdocs.pm and MDN

There's also the user-contributed (but Dash-hosted) docsets: https://zealusercontributions.vercel.app/

Dash makes it really easy to pull docs from readthedocs.org also, this is something devdocs does not have.