The Treasure of "Nun"

If we read the few scattered ayaat of the story of Yunus known also as  Saahib-ul-Hut or Dhun-Nun, we'll see they are not enough to understand the story. We don't know what was the sin his people committed; why and when he got angry; the mistery of being swallowed by the "fish", why Allah SWT pardoned his people unlike other people after they sinned, and so on...

The principle or relevance and my trust in the Qur'an make me believe that the story of Yunus is completed elsewhere in the Qur'an under the name of another prophet. How can we understand it otherwise?

When I recently read:
 نۤۚ وَٱلۡقَلَمِ وَمَا یَسۡطُرُونَ  [68:1]

I thought, "What if the letter ن (nun) is a marking that points at Dhun-Nun?" It seems strange why Allah SWT swears by something that is written after emphasizing ن. Please pay attention to this!

I jumped to the ayaat where the story of Dhun-Noon is mentioned and noticed something really intriguing and fascinating. I think there's a treasure hidden in 21:87-88, that can lead us to Dhun-Nun.

وَذَا ٱلنُّونِ إِذ ذَّهَبَ مُغَـٰضِبࣰا فَظَنَّ أَن لَّن نَّقۡدِرَ عَلَیۡهِ فَنَادَىٰ فِی ٱلظُّلُمَـٰتِ أَن لَّاۤ إِلَـٰهَ إِلَّاۤ أَنتَ سُبۡحَـٰنَكَ إِنِّی كُنتُ مِنَ ٱلظَّـٰلِمِینَ ۝  فَٱسۡتَجَبۡنَا لَهُۥ وَنَجَّیۡنَـٰهُ مِنَ ٱلۡغَمِّۚ وَكَذَ ٰ⁠لِكَ نُـۨجِی ٱلۡمُؤۡمِنِینَ

Please check it out and let me know what you found. There is much more to dig out!