I understand that she physically healed Gon via the wish that Killua asked of Nanika, but there are a few things that were possibly not "healed".
- Gon's Nen ability
As far as we know Gen has lost the ability to use his Nen because of his fight with Pitou. I know there has been some speculation that Gon could have this ability back already but will need to train all over again to gain access to it. Would it be a dumb theory that Killua could use Alluka to also explicitly wish back Gon's ability to use Nen?
- Gon's Penalty
This is something that is little talked about but during that fight Gon somewhat created a rule similar to Kurapikas in the sense that he would give up "all of it" just so that he could kill Pitou. This sacrifice looks like it was supposed to kill Gon for that momentary trade in power, the only reason him being alive due to the life support after the fight and Killua's wish to Alluka. Is it possible that the exchange for that power has been nullified by Alluka healing him?