go.hid | Provides communication with USB Human Interface Devices | Change Data Capture library

Here's some remarks about your code:

1. Inside getter of the Instance property you have a line of code: instance = go.AddComponent(); The point about this line is that AddComponent<> will cause creation of the script's instance and then calling Awake() method. So you will create an instance of your sript by this line and it doesn't matter what's written in the Awake() method. So you can get rid of Awake() as it does nothing. The only case it will do some helpful work is when you'll try to create the first instance of your script (it'll just set the value of instance to the 1st instance). In other cases it's useless. So if you will create your singleton only by using Instance property - you do not need that awake.

2. Awake itself is a "kinda constructor" for MonoBehaviour scripts, but it performs differently. The point is that in pure c# you can easily implement singleton with the help of static constructor but you can't do it this way in MonoBehaviour. That means if you already have an instance of your singleton and you'll try to create your singleton instance with the line T myNewInstance = new T(); the second instance will be actually created. So your code won't protect you from direct creating of the instance.

3. Also, if you'll use gameObject.AddComponent() method, your singletone code won't prevent Unity from creating new script instance.

So, there's no 100% method to create a MonoBehaviour singletone in Unity, but there are some possible workarounds.

For example, take a look here. This solution has much similar to yours but it also uses public T GetOrAddComponent (this Component child) where T: Component helper extension method, which you can borrow to your solution.

Another possible solution is that you can create a non-MonoBehaviour derived c# singleton class like a wrapper for getting a MonoBehaviour class, which you want to have only a single instance. But you'll have to use only this wrapper to manage this MonoBehaviour class, otherwise you will be able to create as much instances of the MonoBehaviour as you wish.