Theoretically this should be possible. I recommend to have a look at the basics of GDScript. At the moment I also get to know the engine. I also know C++ and Phyton. And I prefer C++ too. But simple things can be done in Godot much faster with GDScript. GDScript resembles Phyton anyway, you won't have a hard time learning it.
- compile time is very long with C++ (testing your module needs much more time, than hit F5 key with GDScript)
- with GDScript you have a much easyer posibility to get access on different objects.
- You can create reusable nodes by copy and paste the script (and instancing it).
- if you want high performance e.g. for terrain generation you can write a prototyp in gdscript, to check your algorithm and after that write your module in c++...
- try the shader language, its very close to C and can do very interessting things^^
The Question is not: c++ vs gdscript. In my opinion you should use both, if you can combine advantages of both :)