I don’t see how this is a federal issue. There is a constitutional dimension, if for example zoning codes were used to discriminate against families with LGBT members. But in general? Regulation of land one of the archetypal state issues.
But in general, housing affordability is a federal problem insofar as the federal government already subsidizes housing and transportation. Since the federal government already subsidizes housing (mortgage interest deduction, imputed rent exemption on income tax, and capital gains tax exemptions for the sale of houses), it has an interest in ensuring that these funds aren’t wasted on bidding up land prices in high-rent areas, and it has an interest in ensuring that these funds benefit both the rich and the poor. And since the federal government already pays for transportation, it has an interest in ensuring that these transportation infrastructure isn’t wasted on exclusionary cities.