You asked the knowledgeable people.
But meanwhile:
From what I came across, there is traditionally no 'z' sound in Bharatiya languages. It trickled in from Urdu. The Persians had long had a 'z' though, perhaps it had exercised some influence in the very NW in earlier times? But Samskritam does not have a 'z'. Similarly, Bharatiya languages don't have an 'f' either.
Something I found interesting was that the Nepalese family I knew pronounced the English word 'zero' as 'gero' every single time.
But meanwhile:
From what I came across, there is traditionally no 'z' sound in Bharatiya languages. It trickled in from Urdu. The Persians had long had a 'z' though, perhaps it had exercised some influence in the very NW in earlier times? But Samskritam does not have a 'z'. Similarly, Bharatiya languages don't have an 'f' either.
Something I found interesting was that the Nepalese family I knew pronounced the English word 'zero' as 'gero' every single time.