A method for performing wireless communication by a first device and an apparatus for supporting same are provided. The method may comprise: receiving, from a base station, information related to a first sidelink (SL) resource and information related to a first physical uplink control channel (PUCCH) resource; transmitting, to a second device, a medium access control (MAC) packet data unit (PDU) by using the first SL resource, wherein the MAC PDU includes a packet related to a logical channel for which hybrid automatic repeat request (HARQ) feedback is disabled, and wherein the MAC PDU includes no packet related to a logical channel for which HARQ feedback is enabled; determining that retransmission of the MAC PDU is required; and transmitting, to the base station, NACK information by using the first PUCCH resource based on no SL grant available for retransmission of the MAC PDU.