A method for performing wireless communication by a first device, and a device for supporting same are provided. The method may comprise: transmitting, to a second device, at least one physical sidelink control channel (PSCCH) and at least one physical sidelink shared channel (PSSCH) related to the at least one PSCCH; receiving, from the second device, at least one sidelink (SL) hybrid automatic repeat request (HARQ) feedback information through at least one physical sidelink feedback channel (PSFCH) related to the at least one PSSCH; and determining a priority value of physical uplink control channel (PUCCH) transmission for reporting the at least one SL HARQ feedback information to a base station, based on at least one priority value of the at least one SL HARQ feedback information.