The Frisian pronunciation of Lys is: /'lis/I was unable to find audio clips to prove it to you, but I can tell you that the name is basically the Frisian cognate of the Dutch name Lies, which also has the exact same pronunciation.Also, Lys is not a diminutive, as it does not contain a diminutive suffix. It is simply a short form; the Frisian diminutives of Elisabeth are Lysje and Lyske.
I was unable to find audio clips to prove it to you, but I can tell you that the name is basically the Frisian cognate of the Dutch name Lies, which also has the exact same pronunciation.
Also, Lys is not a diminutive, as it does not contain a diminutive suffix. It is simply a short form; the Frisian diminutives of Elisabeth are Lysje and Lyske.