We do already have this in the UK post partum, although there's also the ongoing matter of childcare, which judging by headcount at school pick-up time still leans heavily female today anecdotally.

That wouldnt "solve" the paygap, women still need to be out of the workforce for O(1yr) per child. That would be an "individual" pay gap of around 10% for a women who has two children.

allow is not enough, it would have to be required. otherwise couples are still under pressure to let men work and let women take the leave.

In the UK it essentially is, one of the two parents can take the full parental leave. It does not have to be the mother. Guess who still chooses to raise their kid instead of creating shareholder value in bullshit jobs most of the time.