A Sikh cremation is followed by an Ardas and by the reading of a sehaj path or an akhand path over the following days, ending in a bhog. Kirtan Sohila is recited. The ashes are usually immersed, commonly at Kiratpur.
The Rehat Maryada is explicit that no other rite is required: no cremation ceremonies beyond the Ardas, no shraadh, no pind, no ritual feeding.
In practice a great deal else happens. The antim ardas gathering is a major social event with a large langar. Village custom around the mourning period, the covering of the head, and the sequence of visits is closely observed.
The custom of a chadar being placed on the eldest son's head at the bhog, marking the succession to the head of the household, is not prescribed anywhere and is near-universal in rural Punjab.
The gap between the Maryada and what a village actually does at a death is one of the clearest illustrations of how religious codes and social practice coexist without either giving way.
The body is cremated the same day where possible, the ashes are collected and taken to a river, and Kirtan Sohila is recited. There is no prescribed mourning period in the Sikh rehat.
What actually happens is a bhog, the completion of a reading of the Guru Granth Sahib Ji, usually on the tenth or thirteenth day, with the village present and a langar served.
The cost of that gathering is substantial and it is expected. The reform movements have argued against the scale of it for a century and the scale has not come down.