How to use retrieve data from Algolia with Firestore

I am using Firestore for my Android App. After designed my app and after adding all the filters now I want to implement full-text search in my app. I used Firebase functions to add the data of firestore to Algolia. I successfully integrate the data of Firestore and Algolia. Now I want to develop front-end for my application. For that I refer documentation from Algolia site. They have separate SDK for Android platform. But if I implement the same then I have to retrieve whole data from Algolia. Now I have already did all the filtering and query requests from the Firestore. So it will be very difficult for me to query the whole data from Algolia and not using Firestore query anywhere in my app. It will also be very costly for me as cost for requesting data from Algolia is very high. Is there any other way that I can still work with Firestore query and Filtering and when any user click on Search icon only then service of Algolia will be in use. I know it can sound something weird but reality is even I don’t know what I want to ask here exactly. In simple sense is there any way that I can search in Firestore data through Algolia and then retrieve the data from firestore.

What you just described is exactly how Algolia is supposed to work and be used.
Your main database (in your case Firestore) is your main source of truth and should remain your main source of truth.

Algolia is supposed to be a copy of your data, which you can search on from your front-end.
This is where the product shines, because of its speed to return results compared to any database system.

You should replace your current requests to Firestore with Algolia only when it concerns search, not for the rest of your website.
If your website has enough usage that this brings you above the limits of the free plan, then we have the Starter plan starting at 29$ / month and scales with your usage.