surya90 AI search is completely different from voice search.
For simple voice command: (I guess the CodeCanyon script you are talking about does the same)
You can just you Google Inbuilt (browser/android) or any native phone's api to record the voice and print the text with voice recognition on the search bar and trigger the search (this is simple)
If you want AI on top of this, then the best way is to do with a 3rd party search engine like Angolia
(Angolia will sync all your products/items/restaurants names and then when you do a text search or voice search and pass that data, you will get better results)