Storing data for Firestore substring word search: string or array?

I am building a Firebase Firestore project, and wondering the best way to store data for Algolia substring search. Let’s say, for example, I store restaurant information and I want to find all menus that contain a certain word “pizza” … is there any advantage to using an array vs string field?

menu: “hamburger, hot dog, pizza, etc” ← store as string
menu: [0:“hamburger”, 1:“hot”, 2:“dog”, 3:"pizza] ← store as array

Update: I answered my own question … I hooked up Firestore to Algolia and and was able to search data stored as strings (full text, substrings) without problem.