Polydamic manufactures FRP molded grating with 1-inch mesh size. The top surface can be gritted to provide anti-slip property. It comes in standard size of 4ft x 8ft.
If you find up-keeping and maintaining mild steel platform or walkway a complete hassle due to chemical corrosion, why not use FRP molded grating instead? It is durable, chemical resistant and costs lesser than Stainless Steel.