Another good app is Nirvana, I've never used it personally, but lots of GTD people do

That should say Omnifocus 😖

That's a great book, and if you're looking app with the GTD method built-in, check out Omnificus. It ain't cheap but it's mature and feature rich. There's a steep learning/setup curve, but you have that sorted the flow is great!

Now this is interesting. Definitely getting put on the list!

Ooooh I'll look into this one!

Already have it! Playing a Humblewood campaign now! So fun!