Heat a grill or grill pan over medium-high heat. Grill the pineapple rings for 2–3 minutes per side until lightly caramelized. Let cool, then cut into small cubes.
In a medium mixing bowl, combine grilled pineapple, diced mango, bell pepper, red onion, cilantro, lime juice, and salt.
Stir well and let the mixture rest for 15 minutes so the flavors blend together.
Preheat the oven to 400°F.
Arrange baguette slices on a sheet pan and brush both sides lightly with olive oil.
Bake for 10–12 minutes or until golden and crispy. Check after 7–8 minutes to prevent over-browning.
Spoon the Pineapple Mango Bruschetta mixture over the toasted bread slices.
Serve immediately while the bread is crisp and fresh.