It depends on the site but when I was a SAHD, I found many of those parenting sites were not welcoming to dads, even dads doing the exact same work as the moms. Moms there wanted a place to vent about their husbands and men who were pulling their fair share or were handling most of the parent duties simply weren't allowed.

This, it's well known that women want to vent and men want to fix the issue. This difference in communication and perspective has been supported in various research.

one of the better places I found found was Daddit on reddit, though I haven't been in a while.