I read that newborns mainly pee and might poo as seldom as once or twice a week.
My friend just had her son && he's breastfed she said he poop 2 times a day maybe 3 and the rest is pee. I heard breastfed babies poop more I might be wrong idk im a ftm Im just going off what I seen & heard.
If your baby isn't pooping at all it might be your diet, some things you eat might be causing that. If your baby seems constipated there are always medicine you can give them.