Laravel relationship between 3 tables where 2 are connected via pivot - laravel

Question

I am new to Laravel and looked already for a similiar thread but I didnt find something.
I want to use Eloquent and I got 3 Models and Tables: Testseries, Devices and Users.
The Users has a many to many relation to devices. (One User has many devices and vica versa)
And Devices has a one to many relation to testseries. (One Device has many testseries and many testeries has one device)
**
Table structure Users:**
id
username
Table structure Devices:
id
serial_number <-- its a string, not important for the structure
Table structure Testseries:
id
device_id
Devices and Users are connected via Pivot
device_user:
id
user_id
device_id
If a User is logged in, I want to show all Testseries from all Devices that are connected to the User.
I defined in the User Model:
public function devices(): \Illuminate\Database\Eloquent\Relations\BelongsToMany {
return $this->belongsToMany(Device::class);
}
And in the Device Model:
public function users(): \Illuminate\Database\Eloquent\Relations\BelongsToMany {
return $this->belongsToMany(User::class);
}
public function testseries(): \Illuminate\Database\Eloquent\Relations\HasMany {
return $this->hasMany(Testserie::class);
}
Is there any way to create function inside the User Model which can easily access to the testserie?
If someone doesnt understand what I want because my English isnt good. This function should tell what I want inside the User Model:
public function testseries() {
return $this->devices()->testseries();
}
Also I want all testseries at one query.
I tried with the each method. But its doing for each device a single query to the testserie.
I also tried it with the with method. It works, but I want all Columns from the Testseries Table, but then I have to tell all table names inside the array and I dont want the columns from the Devices table.
I expected to get a query when I call the ->get Method that I'll get all Testseries at once with a single query.

Answer 1

Try this :
Auth::user()->with('devices.testseries')->get();

Answer 2

I found a way,
I added this function to my User Model:
public function testseries(): \Illuminate\Support\Collection {
return Testserie::whereHas('device', function(Builder $query){
$query->whereHas('users', function(Builder $query){
$query->where ('user_id', '=', \Auth::user()->getKey());
});
})->get();
}
This works. I dont know if its the cleanest way. If someone has a better way. Dont be shy to share your thoughts.