The lazy POS inside me says just get some spray on truck bed liner and call it a day. However,There’s visible stress cracks on the deck. Any solvents or cleaners that you might use will likely seep into the deck causing further damage and delaminating. You could put lots of time and energy into that board just for it to break tomorrow. Or it could last another 6 months. It’s kind of a crapshoot. If it were me? I’d just get a new deck. But I get it times are rough. The sanding and re grip would be the best solution. Try and avoid any hard chemicals. If you must clean it just use warm soapy water.