Amazing!
Professor Edwin Barnhart in The Great Courses: Lost Worlds of South America (copyright 2012) discuses Khipu(s?) in Lecture 21. He states, “Some scholars believe that they (khipu) are simply accounting devices, while others believe that they constitute a true writing system. It seems unlikely that an empire like that of the Inca could have been managed without some kind of writing system.”
Deciphering such a writing system without a similar Rosetta Stone would be another real challenge.
I’ve listened to all his lectures, too. Iirc, he said he believed khipu would be deciphered within the next 20 years, and we’re about halfway through that period.