The answer is yes, you can use a fence sprayer on decking. However, the type of paint you need for your decking project will depend on the surface material and desired finish. For example, if you are using treated wood then a water-based deck stain should be used instead of traditional fence paint. If you are using composite decking, then you will need to use a solvent-based or oil-based deck sealer.
When using a fence sprayer on your decking project, make sure you follow the manufacturer's instructions and wear protective clothing. Also, be sure to cover any nearby plants or furniture that could be damaged by overspray.
Finally, be sure to keep a garden hose or bucket of water handy in case you need to rinse off any excess paint. With these precautions in mind, you can confidently use a fence sprayer on your decking project and achieve the desired finish.