Usually not. Work on private property is the owner’s responsibility and generally ineligible, with rare exceptions where you have legal authority to do it. If another federal agency has more specific authority over a facility or type of work, FEMA will not fund it, even if that agency does not pay. Apply to that agency instead.
Your legal authority for any work on private property, such as the statute or ordinance that allowed it; for work outside your jurisdiction, the agreement or legal basis; and any correspondence with another federal agency about whether its program covers the facility or work.
Federal-aid highways (FHWA Emergency Relief) are the classic example: FEMA will not fund them even if the other agency’s funding falls short. Identify any overlapping federal program early and file with that agency on time.