Nanite making my meshes super low poly and causing shading issues

Yes, although I’m not entirely sure how. Regarding the nanite polygon scaling issue I have done some additional data-prep to the file and the issue seems to be resolved, I assume it might have been an issue with transforms not have been frozen/applied before importing into UE5.

Regarding the shading I believe the following Console Var solved the issue:
r.Raytracing.Shadows.EnableTwoSidedGeometry 0