Is a deceased person held accountable immediately after the soul departs, or after burial? And what is the meaning of the hadith "Ask forgiveness for your brother; he is now being questioned" if accountability is after the soul departs?

It has been established that the deceased is questioned in their grave, based on the Prophet's (peace be upon him) saying: "Ask forgiveness for your brother and supplicate for his steadfastness, for indeed he is now being questioned." Matters of the grave and the questioning by the two angels are among the unseen (al-Ghayb) which must be believed in as stated in the sacred texts. The torment of the grave is the torment of the Barzakh (definition) (intermediate realm); thus, everyone who dies deserving of punishment will receive their share of it, whether they are buried or not. As for specifying the time of questioning and whether it is delayed for a deceased person whose burial is postponed, that is something which cannot be answered.