The department shall develop and, subject to specific authorization and appropriation by the Legislature or the availability of federal subsidies, implement demonstration subsidy programs to test the effectiveness of one or more housing subsidy programs for veterans, very low income households, or other persons and families of low or moderate income. Such programs may include housing allowance payments, homeownership downpayment assistance, homeownership interest subsidy, leased housing subleased to very low income households, rent supplement payments on behalf of very low income households, or other types of subsidy programs.