@Blue_Morpho I don't use Orca; I use PrusaSlicer. I haven't really compared the two ways to decal, no. I haven't had problems with bad slicing.

You can also try exporting a .STEP file from Fusion. .STEP retains even more information about your intent than .3mf.

.stl: just triangle meshes
.3mf: triangles + assembly
.STEP: BREP (solids, faces, edges, etc.)