Imagine what happens when a hose breaks, the washer leaks (bad seal), wet clothes drip, etc. I'm not sure storing anything UNDER a washer is a good choice.
The store-bought pedestals don't appear to be good for much. E.g., our detergent bottles are too tall to fit inside them. And, would require you to bend and lift gallon jugs each time you wanted to do wash.
We prefer to use the space atop the washer dryer (to fold clothes, sort through items going in/out, etc.).
But, have cabinets there so with the W/D "up", we lose that space.
As the W/D really only need to be "up" for loading/unloading, I'm looking into installing scissor lifts under each appliance so they can be raised and lowered, as needed. HF has some lifts that might be easily repurposed.
[This also addresses my "accessibility" concerns as someone aged with scoliosis or powerchair-bound would want the appliances at a different height. It also deals with the inevitable "we need to get the washer dryer *down* so we can service it"]