“Conservation groups, led by the Animal Legal Defense Fund and the Center for Biological Diversity, argued that the Illegal Immigration Reform and Immigrant Responsibility Act of 1996’s provision giving the Homeland Security secretary nearly limitless authority to waive laws in the name of building border protection infrastructure like walls is unconstitutional.
...The 1996 law and subsequent amendments to it give the Homeland Security secretary the power to waive any law — not just environmental ones — in order to facilitate building border infrastructure like fences and roads.”
The Supreme Court left the power to waive any law to build a border wall intact. Funding is the only obstacle.
Cool. Waive any law blocking funding via military budget or whatever works best.