Can you cook the pineapple the night before? And / or make dressing? Going to a dinner party and short on time the day of the party.

You could make it in advance.
But the recipe looks like it depends on the materials being freshly grilled, cut, combined for best taste and texture.
Maybe consider another salad that would hold up better to a day in the fridge...French composed (various), Russian mayonnaise layered, classic Cole slaw (with dried fruit, nuts and colorful veg garnish), German potato salad.