It varies. Vast majority are on the GS scale but some are hired under the Cures (Title 21).
FDA ‘attorney’ positions are classified as 0905 series and are in the Office of Chief Counsel, not the Office of Policy (although many people in this office have law degrees). Some attorneys are remote but I do not know if they are actively hiring remote employees. The Office of Policy goes into the office 2x a pay period (typically once a week).