Pretty much every embedded database since about 1988 has worked like that.
You say that being an embedded database isn't the main selling point, being contained within a single file is. But that's a completely normal feature of an embedded db, to the point that the one implies the other.
You say that being an embedded database isn't the main selling point, being contained within a single file is. But that's a completely normal feature of an embedded db, to the point that the one implies the other.