is there anyone alive in this world currently who will not receive a single Gunah in Jahannam, if I understand the question correctly the question is asking that, is there anyone currently living who will not get a punishment for single Gunah in jahannam?
the answer is different if the question is, is there anyone living today who has not done a single sin?
then the answer is the only people who are sinless are the Ambia The Messengers of Allah subhanahu tala.
So I don’t know if anyone living today in the world, who has not done a single sin. but if the question is that is there anyone who will not receive punishment in the Jahamnam?
inshallah there’ll be many if Allah subhana wa ta’ala wants to forgive someone, even after he has committed sin. if the person repents insh Allah is Rahmanur rahim gafurur rahim and there are various Hadith in which the prophet said that if the Servants of Allah sin during night and if they ask for forgiveness in the morning Allah will forgive them if they sin the full day and they ask forgiveness in night Allah will forgive them.
