This is what I use on my organic lawn.
Ive had really really good results with the Purely Organics fertilizer from home depot. It's made from waste distillery grains.
https://www.homedepot.com/p/Purely-Organic-Products-25-lb-Dry-Lawn-Food-Fertilizer-LFJRDK1/204279747
For weeds I have had good look with Tenacity which is all natural and derived from the bottle brush plant.
Tenacity herbicide can be used for pre- and post-emergence control of more than 46 broadleaf weed and grass species. Its active ingredient, mesotrione, is based on a naturally occurring compound produced by the bottlebrush plant (Callistemon citrinus) that inhibits photosynthesis in susceptible plant species. It is absorbed by plants through the roots, shoots and leaves and distributed throughout the plant by both xylem and phloem translocation.
Active Ingredient(s): Mesotrione