I know you can do GTD with paper, apps, etc. I know it’s the system and not the app but I am amazed at this article on using Google Sheets.
That’s an impressive use of Google Sheets. I reckon that a Mac user could do something similar using Apple’s Numbers and iCloud.
This is intense and yet simple. I have a handful of cases where I access Sheets on my iPhone. It’s not a far stretch to see how that could become an easy way to view lists.