I guess if you're willing to sacrifice some things it could work. You're definitely not raising a family of 3-4 in a nicer neighborhood with that amount.
I don't think there is one correct answer to the question of how much money you have to have to live, because it's mostly about your biggest expense, imo. Everything else you can economize on to an extreme if you have to, if you're healthy and sane and frugal.
Once you start talking about a "nice" neighborhood, you're talking about a competitive zero-sum game where the costs can increase without limit.
Having an income of 20k/year in US puts you at like 16th percentile.
That is assuming your status is above subsistence level in your society.
We're all pretty bad at knowing what will make us happy in advance.
With kids, the cheaper areas have generally worse schools, parks, etc.
The neighborhood they were living in was generally fairly average, everything considered. But only one of them had one kid (also single parent though).
Not in a large city. But I’m fairly sure in that case the main downgrade would be the neighborhood.