I am trying a similar workflow, and the Collada format seems to be the best one to maintain textures and geometry. The only drawback being that the object interface does not provide an easy way to remove the edges.
To remove them, open the object GDL script editor (cmd+alt+O), go to the 3D script and Find and Replace (cmd+F) "-1, -1, 0" by "-1, -1, 1" and select Replace All.
When you save the object, the edges will disappear!
Archicad 26 ARM, MacBook Pro M1 Max 64Gb, macOS Monterrey.