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
Materials and textures from Blender to Unity 3D | Edy's Projects
Blender to Unity Best FBX Format Settings - Soja Exiles
Blender to Unity: How to Export/Import Models | All3DP
How can I export from unity to blender? - Stack Overflow
Materials and textures from Blender to Unity 3D | Edy's Projects
Exporting Multiple Animations from Blender to Unity – ZuluOneZero