Is it permissible for an unmarried person to break their fast on the Eid sacrifice according to all madhhabs?

It is sunnah for the one offering the sacrifice to refrain from breaking their fast until they eat from their sacrificial animal. This is based on what Al-Tabarani narrated from Buraydah (may Allah be pleased with him) that the Prophet (peace and blessings of Allah be upon him) "would not eat on the Day of Sacrifice until he returned and ate from his slaughtered animal." The jurists have agreed upon the desirability of delaying breaking the fast on the Day of Sacrifice in order to eat from the sacrificial animal.