1.txt

// ☁️ Admin node
admin.database().ref().child("test").child("Admin")
    .once("value", snapshot => {
        Object.values(snapshot.val()).forEach(value => {
            console.log(`(${value.hoge}, ${value.fuga})`);
        });
    });

// 🍎 iOS Swift
Database.database().reference().child("test").child("iOS")
    .observe(.value, with: { snapshot in
        snapshot.children.allObjects
            .flatMap { ($0 as? DataSnapshot)?.value as? [String: Int] }
            .forEach { print(($0["hoge"] ?? -1, $0["fuga"] ?? -1)) }
    })

// 🤖 Android Kotlin
FirebaseDatabase.getInstance().reference.child("test").child("Android")
    .addListenerForSingleValueEvent(object: ValueEventListener {
        override fun onCancelled(p0: DatabaseError?) {}

        override fun onDataChange(snapshot: DataSnapshot?) {
            snapshot?.children?.forEach {
                println(it.getValue<Hoge>(Hoge::class.java)?.hoge to it.getValue<Hoge>(Hoge::class.java)?.fuga)
            }
        }
    })
    
// 🛎 結果はすべて
(1, 5)
(2, 4)
(3, 3)
(4, 2)
(5, 1)