To obtain his adult form to fulfill the condition of beating Pitou, Gon had to give up on something more than his own life and here comes my first question what did Gon sacrifice to transform, People say talent and potential and Nen if that's true after Nanika healed him did he really lose the potential and the talent he had so he is not just Gon without Nen he is Gon without nen, potential and talent?

I think he is just back to start manga gon,talent and all. But regardless,this is mostly a narrative tool togashi used to give consequences to the adult gon transformation, and it worked really well as a punishment for me. Sure,he got healed and meet with ging, but because of what he did, he couldn't go with his father explore the new continent and live new adventures, which is what he likes to do in life. I like this manga.

No, he still has nen, alluka removed the restriction Gon placed on himself. It would be extremely odd for Gon to lose his potential, being a main character and all. It’s possible he did, though, but it’s really, really unlikely. He just needs to reawaken it. Some think his potential grew because of the traumatizing experience aswell.

Gon is obviously the main one of the 4, just stop

he is still physically strong remember him climbing the world tree... but if he lost his potential that he wont be as strong as Adult Gon then that is gonna be amazing for the story however he can still get strong as that by other means.

Use this as you may: when Gon met Ging atop the world tree, Ging said something like, "oh you can't see your nen?" implying Ging could still see it, its just currently blocked for Gon

Gon sacrificed (or rather, used up) all the aura he would ever have over the course of his life in order to transform. Nanika reverted him to a state before his Nen pores were opened by Wing.

He'll get it back but there better be hell to pay for it. Gon still doesn't know Kite was reborn as a chimera ant, hasn't met Gyro. He is aimless now and doesn't seem to desire power again but when one of his friends are in a pinch he would regret becoming powerless. He will probably set out on a quest to regain his nen. I feel like his vow to use everything has 2 aspects, using up all his lifeforce and nen, which left him physically shriveled and unable to use nen. Alluka's powers are kind of cheat so she was able to give Gon his health back. He probably has to have an exorcist or some special vow/ritual restore his ability to use nen. Maybe a vow even more severe than the one he took before, or some kind of loophole/compromise. Like being granted access to nen for a short amount of time in exchange for lifespan/memories/idk