If I might make a suggestion related to the gaps that you mentioned that motivated the tool...
It's hard to communicate the real importance of learning scales and chords at the same time. Specifically, learning all of the important scales and then building chords from those and finding more fingerable/playable voicings for them. Even going as far as removing strings and still trying to complete the scales/chords and then alternate tunings, etc. It's really a slow grind that there's no shortcut for.
Most players skip a lot of this important early practice because it's about the furthest thing from playing songs on the guitar like they want to.
Doing something like classical guitar lessons might be extremely helpful/humbling. Variety also helps -- I got a lot better once I started playing in multiple tunings and different kinds of guitars (#strings, baritone, etc) -- heck I'm learning the Stick right now.