Can one effectively learn the kriyas or techniques without initiation? Understanding what has been discussed above, the answer is, it depends on the qualities and karma of the individual, but it is highly unlikely. It would require Divine Grace and unrelenting faith. There is an essential sacred transmission of consciousness and energy, which empowers the techniques. That is why initiatory traditions have managed to pass the direct experience of truth from one generation to the next so effectively. Their strength lies in the power and the consciousness of those who have done the practices intensely and so realized their truth. We honor our highest Self when we honor our initiation by putting into diligent and regular practice what we have learned and received in them.''
Hong Sau and other techniques can lead to Samadhi. That doesn't require initiation, even in SRF.
Babaji's Kriya Yoga has initiations, but I don't consider anyone my guru.