Hi there, guys. It's always fun to experiment. Let me know how it turns out for ya.
I'll throw in a couple thoughts about your situation, but please don't take it as criticism.
If you are looking to add sweetness to your wine, you only have to add some kind of sugar (table sugar, honey, fructose) after fermentation, or stop fermentation before all the natural sugar is used up by using certain preservatives or fancy filters. I think ascorbic acid is one preservative I've heard mentioned.
If it's not just the sugar you want, but are after the different flavors and aromas, this should be easier to solve through grape variety selection. Good Chardonnay grapes (note I said good) should already have some pineapple and citrus aromas, which the variety is known for. Recently I opened a bottle of 1994 Hawk Crest Chardonnay that still had wonderfully powerful citrus and tropical fruit aromas, including pineapple, combined with the oak. However, Chardonnay is not really known for having powerful aromas in the first place, which is why winemakers so often age it in oak to add some complexity. If you like tropical fruit, there is a French Hybrid called Vignoles which is known for this character.
If you're kinda stuck with using the kits that are available, then I can understand. I'd be afraid that canned pineapples wouldn't "fit in" or harmonize with the other aromas already present. If anything, you might want to try fresh or even frozen fruit.
If you prefer a fruit-driven wine, then in the future you might also want to try and find other varieties such as Riesling or Muscat. They can have tropical fruit aromas depending on how they're grown, in addition to other delicious flavors.
