Seeing ENDED is not exactly encouraging.
In Europe, you can sometimes still get an ENDED part. My dealer's parts guy snagged a discontinued trim strip for me from across the border in Poland. If he hadn't, the warehouse in Dingolfing could only send an entire seat back.
I have no idea what can be done in the U.S., or whether someone would risk holding a specific and fairly expensive piece.
EDIT: I don't know what this suggests as possible, but my ENDED trim strip came from a regional BMW warehouse in Slubice, Poland.