Any locality may participate in a program under § 8 (Housing Assistance Payments Program) of the United States Housing Act of 1937, as amended, on behalf of eligible families or eligible persons leasing privately owned housing directly from owners or private leaseholders. Any such locality may also appropriate its own money for the same purposes for which federal funds may be employed under the provisions of such federal legislation as well as for the purpose of increasing the payments to eligible families or eligible persons beyond federally approved levels when the fair market rent of the rental unit is greater than that established by the United States Department of Housing and Urban Development. If any power granted in the foregoing paragraph is held invalid, the other remaining power shall not be affected thereby. If the application of the power granted in the foregoing paragraph to any persons or circumstances is held invalid, the application of the power to other persons shall not be affected thereby. Nothing in the foregoing powers granted localities includes the authority to pledge the full faith and credit of such locality in violation of Article X, Section 10 of the Constitution of Virginia.