Kiya's name appears to have been a pet form, or a nickname, possibly for a foreign name such as Gilukhipa or Tadukhipa. If the name was indeed foreign, then it stands to reason that Kiya herself was not Egyptian. This is somewhat substantiated by the fact that Kiya is never referred to as "heiress" or "cheif wife", suggesting that she wasn't of Egyptian blood. On the other hand, other than the unusualness of the name itself and the (non-)references to her, there is no evidence to support the theory that Kiya was foreign-born. I could not find what Kiya could mean, in any case, nor what Gilukhipa or Tadukhipa means.
Kyah could be a modern respelling of Kiya.
Miranda "Multiple exclamation marks are a sure sign of diseased mind" -- Terry Pratchett
Proud adopter of 15 punctuation marks. Check my profile for their names.