Often this is taken to imply a personal perfection in the ability to know past lives or fly. But these are not personal.
As Lorne Hoff has pointed out, the siddhis are perfections of experience, of the ability of consciousness to know itself in specific ways that this form is capable of. Each channel of knowing is a function we can call a law of nature, a way nature can express to know itself in a specific way.
We might think this makes you a “law of nature” but you are a gathering of laws of nature in a specific mix of emphasis. This creates a style of experience that is unique to this form.
The point of the siddhis is thus not a personal experience of some flavour or effect but rather in the perfection of experience by being able to embody a law of nature. This is True Samayama to allow a specific law of nature to experience fully through this form. That does require we be awake so that the identification with a limited sense of self isn’t an impediment.
It’s worth remembering that the process of experience (and creation) is the forum of laws of nature. They are the doers of the world. Everything happening and everything you experience is being done through teams of laws of nature.
If we can step fully into that flow of expression, we give the ability of full expression to those laws, fulfilling their purpose. This is siddhi or perfection.