Firing up Xaramin and adding each of my *.cs files into the new project. I found there were actually very few issues building the actual C# code. The issues showed up when I was building the content using the MonoGame Pipeline tool.
So the initial results.
- Textures: Compiled no problem.
- Models: Required I exported them using the Binary exporter in Blender.
- Shaders: …..Some worked, some…not so much.
- Audio: Didn’t try yet since shaders essentially exploded.