I think Liverpool giving out mane to bayern without bringing another top striker like him will actually affect the club, because mane has been a good and competitive striker at the club which was performing great and lifting the club as well. So i don't think mane absent wont affect the team.
Overall, yes, if Mane leaves it won't have much of an impact on the team, but there will be a re-adaptation in the front sector because it puts new players in. Nunez's arrival was for that, to fill the void left by Mane. So Liverpool have signed good players to replace good players. I hope Nunez can quickly adapt to the Liverpool game.