An offline lifesaver: Dash.
I found and purchased Dash, an offline documentation library and lifesaver.
Fearful, I grabbed everything I could possibly think of and overstuffed the library with digital dust collecting doc after doc after doc. (Hey! I may need to look up an Arduino method.)
I use Dash to this day, and found it fundamental to developing while offline.
Thank you to the Devs and Documentationists (or Writers or whatever) who put the words and examples and doc frameworks and everything together.
A modern human, I still needed to internet from time to time.
How to manage this?