LayDhammaFollower asked: Faculty Of “I will know the unknown” means having Chanda for nibbanā and trying to have asavakhaya nana, right?
No, anaññātaññassāmītindriya is the wisdom faculty “I will know the unknown” or “competent of what has so far been unknown” when Sotāpatti is reached. See the “Wisdom faculty (paññindriaya) of Lokuttara (supramundane) Chart” above at the top right corner.
Kindly note that when reaching the Sotāpatti fruition, if you have not been able to reach jhāna till the fourth jhāna (for sutta) or fifth jhāna (for Abhidhamma) and have ability to review the five jhāna factors and know which jhāna a yogi is in, you will not be able to review the thought process (paccavekkhana vīthi) of these three wisdom faculties (anaññātaññassāmītindriya, aññindriya, and aññātāvindriya).