Pronunciation of 'has' (/z/ or /s/) before /tʃ/

Solution 1:

This is wrong, at least in the U.S.

In the U.S., the pronunciation of has is /hæz/, except when it appears in the construction has to, when it is pronounced /hæs/. He has two leaves: /z/. He has to leave: /s/. See the Merriam-Webster Dictionary.

(The /s/ and /z/ often change their degree of voicing somewhat depending on whether a voiced or non-voiced consonant follows, but this is the case for all /s/'s and /z/'s at the end of a word in the English language, and is not related to the difference between has two and has to. Native English speakers lengthen vowels before a voiced consonant, so for some speakers, the difference between has to and has two could be mainly in the length of the /æ/.)

As mentioned in the comments, in the U.K., the dictionaries say that the pronunciations are /hæz/ and /hæv/, and don't give exceptions before to. But I wouldn't be surprised if some British speakers used the same rules as Americans do.