public override void InitializeAfterDeserialize()

Unfortunately, UnityEngine.ISerializationCallbackReceiver can't be used to automate this because many Unity functions aren't available during serialization such as getting or setting a UnityEngine.Behaviour.enabled like Animancer.FSM.StateBehaviour.OnEnterState does.

Example:

public class MyComponent : MonoBehaviour
{
    [SerializeField]
    private StateMachine<MyState> _StateMachine;
    
    protected virtual void Awake()
    {
        _StateMachine.InitializeAfterDeserialize();
    }
}