More like a whole database table as a JSON file - I split the whole database export into tables using `jq` (an export from Firebase Realtime Database). I generally use sublime text to open them, it's quite happy with anything that will fit in RAM. For very large file it just shows a load bar while it loads it.
It was vital for exploring the shape of our data during a data migration to Postgres as our data was not very regular in shape and firebase's querying capabilities are pretty limited.