States, territories and tribes follow the same procurement policies they use with their own funds, plus the EPA recovered-materials rule, and must include the required federal contract clauses in every contract.
Your procurement procedures or an attorney certification, and contracts showing the required clauses. FEMA’s Contract Provisions Guide gives the exact wording where verbatim language is required.
Even where state law allows them, time-and-materials contracts without a ceiling and cost-plus-percentage contracts carry a high risk that FEMA will find the costs unreasonable.