Development of sustainable biocomposite panels assisted with deep eutectic solvent pretreatment of agro-industrial residue

•Agro-waste is treated with DES to fabricate fiberboard panels.•DES pretreatment delignified the agro-waste to extract cellulose-rich fiber.•Obtained DES-treated fibers had a lower crystallinity than those of untreated fibers.•DES-treated biocomposites exhibited higher bending strength and modulus compared to untreated.•DES pretreatment reduced the dimensional stability of the fabricated biocomposite panels.