I would think that the money, depending on how the fundme was set up could be used to build the wall on private land were possible.
I can’t see a reason this could be stopped.
EPA would attempt to step in probably. Prevention of the migration of the spotted leopard snail or something like that. Impact studies, etc. That is why we would need patriots guarding the contractors (if any could be found to build under those conditions.
If we have no border, we have no nation.