Don’t get hung up on GPL vs MIT if you only using the work product. If you are incorporating a texture design program into an applicaiton, then search.
Gaming textures are freely available from a dozen sites for a dozen gaming platforms: not Godot specific.
VPaint - Vector editor for 2D animation based on Vector Animation Complex technology, developed by Inria and University of British Columbia, presented at SIGGRAPH 2015.
The program allows you to create resolution-independent illustrations and animations using innovative techniques.
The VPaint team takes pride in the fact that it is open source software licensed under the MIT license.
Only one Viewport is used for the 3D scene, and several Viewports (low resolution) with orthogonal cameras for the 2D-Viewports (also low resolution) where the Multipass/Feedback shaders are processed, about them below. All textures have mipmap, and work even in the browser. There are additional graphics settings (Esc - Settings).
