spine-scripts VS spine-runtimes

What do you mean by "blocking out"? You can run PhotshopToSpine script to get art in Spine very quickly, you can use shortcuts such as holding ctrl->selecting image->placing bone which automatically parents the image slot to bone. Then you can use the fairly new Trace feature to automatically generate meshes if you don't want to do it manually.

I know it can be a bit of a pain importing and placing images as a skeleton in Godot. If you do end up going the bone route, you should be able to export your images with a spine.json file using this. I use Affinity so it is built in. Then using this Godot plugin you can import it with all of the parts in the correct location.

There are a bunch of programs that use rigged and meshed 2D images that create these sorts of animations. I have only used “Spline” for game animation http://esotericsoftware.com/

We're using Spine2D http://esotericsoftware.com/ It's really great

It’s rigged 2d animation. Look into spine. http://esotericsoftware.com

That's easy. Spine Pro.

You may have to learn spine separately from their tutorials and then figure out the godot integration from their sample projects: https://github.com/EsotericSoftware/spine-runtimes/tree/4.1/spine-godot/example

From the first glance it seems like Spine provides their libraries in source format (under non open source license) with pure C++, C# and TS implementations that don't depend on binary blobs (at least it seemed like it). You can find it here https://github.com/esotericsoftware/spine-runtimes . Even if C++ version is not safe, C# and TS versions are probably fine and, and the license mentions creating derivative works (assuming you follow the Editor license terms and some of invovled parties have an editor license) so you are probably allowed to create modified library which processes the files safely.

For example Spine: http://esotericsoftware.com/