Is there any Alternative to Firebase to use as a database. Firebase is not exactly ideal in my case because of how many read and write operations happen. And well firebase mostly cares about how many write and read operations you execute, and they charge you that way. I need a database that dosen’t care about how many write and read operations are executed, rather how much data is stored.
You most likely would not find a database service that does not care about read and write counts at all. A read/write is not free, it takes internet bandwidth (which is not free), and a server’s resources (RAM, CPU, etc), and therefore hosts simply cannot afford billing exclusively for storage capacity.
Your best bet would likely be supabase: Pricing & fees | Supabase
Although supabase has unlimited read and write requests, the sum of data transfered across those reads and writes is limited to 2GB monthly. Data storage is also capped at 1GB. It is not very flexible - unlike firebase, where you pay for what you use and can scale to infinity, you got to upgrade directly to a whole 25$ monthly “Pro plan” which is still capped 
Of course, there is no extension for it. There isn’t for anything besides firebase. You would have to use the databases’s REST API with the network request action to send and get data from the database.
This wouldn’t be an easy task, nobody tried it before so nobody would be able to help you.