Here is how to export FBX models to Unity with perfect transform rotation values if you're suing Blender. Works perfectly with rigged meshes too. More details is in the comments. : r/gamedev
animation - Having problem with Blender export into Unity - Stack Overflow
Exporting animated character from Blender to Unity - BlenderNation
Blender 2.82 - Rigify to Unity Tutorial - How to Export a Rigify Character and Import it into Unity - YouTube
animation - Blender to unity fbx export comes out destroyed - Blender Stack Exchange
Exporting Blender Animation to Unity Causes Foot Problems - Unity Forum