I am working on a tower defense title too, but with a catch. I read another thread that someone else is doing a tower defense with satellites. We should have some good tower defense entries in this jam. I can't wait to give your game a try. The design looks really good!
Also, if you need some help with trigonometry in Godot, let me know. The Godot unit circle is very unconventional, firstly because it's flipped along the horizon, but also because the Godot devs flipped the positive semi-unit-circle along the y axis, but not the negative one, iirc!
What this means, is that you need to hard code smooth transitions for the edges of each quadrant with angle offsets like [0, 270, 180, 90] and offset the offsets with -360 when your y position is negative (above the origin) iirc.