It's important to make sure your music theory knowledge grows at the same pace as your ability to play music, to put the theory into practice.

Otherwise you can play things but don't understand how or why they work.  Or you know a lot of ideas that you can't play or use to make music.

All the GT courses have theory integrated with the material.  You will get an understanding of what to play (practice) & why it works (theory).  And how both will help you improve your overall musicianship.  Since they all do this, the best course to work through is the one that motivates you the most to practice.  If you like blues, then do that course.  Or acoustic, same thing.

To get started on a more in depth understanding of how the fretboard works musically you might enjoy working through part of my older GF 2 course.  In particular chapters 1 and 3 focus on intervals, scales, chords & how all those are interrelated.

Start here for intervals and how they are used to build scales.

https://www.guitartricks.com/lesson/10661

And here for how scales are built into chords and how they are integrated on the fretboard.

https://www.guitartricks.com/lesson/11168

Since you mentioned improvisation, these might be beyond your current skill level, but it covers the basics of how improvisation works.  Hint: it has to do with how scales and chords are related!

https://www.guitartricks.com/tutorial/876

Hope that helps.  Best of success!