If you only want to bring in something you've modeled in SketchUp as a GDL object, that works pretty well with all texture mapping retained.
Save the selected elements from SU as 3DS. Use the 3DS importer (goodies folder of 9) of ArchiCAD to import that as an object. The materials are automatically made parameters of the new object.
If you want to bring your SU work in as editable ArchiCAD elements, converting things to walls, slabs and roofs, Graphisoft recently announced that they plan to offer an add-on to do that. I am not aware of a release date.
Karl
AC 28 USA and earlier • macOS Sequoia 15.3.1, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB