I tried different combinations now but there is always this smooth seam left.
I guess it’s something specific to Metahumans.
Your script works perfectly, though.
I imported the head from Unreal into Maya and compared it to the head I got from Quixel bridge and the vertex normals are almost perfectly identical.
No idea at the moment what else to try.
Maybe it’s related to this other issue I’m having: Import Metahuman to Maya from Bridge, head and body disconnected when exporting to FBX from Unreal