The disclosure relates to omniphobic coatings, related articles including such coatings, and related method for forming such coatings or articles, for example biobased and/or biodegradable omniphobic coatings. The omniphobic coating includes a reaction product between an amino-functional polymer and an amino-reactive functionalized omniphobic polymer having a glass transition temperature (Tg) of 60° C. or less. The omniphobic coating has a weight ratio of amino-functional polymer relative to functionalized omniphobic polymer of at least 1 or 2. A corresponding omniphobic coated article can include the omniphobic coating on a porous substrate such as a cellulosic or paper substrate, for example to provide a water- and oil/fat/grease-resistant coating for a paper-based product. The omniphobic coating can be formed in a reaction medium before being applied to the substrate, or the omniphobic coating can be formed on the substrate with serial application of the amino-reactive functionalized omniphobic polymer and the amino-functional polymer thereon. This disclosure provides a closed loop circular economy approach for fluorine-free, water- and grease-resistant paper as the coating can be easily separated from the pulp/fiber of the paper. The recycled pulp can be used for paper making, while the separated coating in micelle form can be used for recoating.