Combine rinsed jasmine rice, water, and salt in a medium saucepan. Bring to a boil, then reduce heat to low, cover, and simmer for 15 minutes. Remove from heat and let stand covered for 5 minutes. Fluff with a fork.
Whisk together pineapple juice, soy sauce, brown sugar, grated ginger, and minced garlic in a small bowl until sugar dissolves. Set aside.
Heat a large skillet over medium-high heat with a drizzle of oil. Season chicken breasts with salt and pepper, then sear for 5-6 minutes per side until golden and cooked through (165°F internal). Transfer to a plate and tent with foil.
In the same skillet, add pineapple rings in a single layer. Cook for 2-3 minutes per side until caramelized. Remove and set aside.
Pour the glaze mixture into the skillet and bring to a simmer over medium heat, scraping up browned bits. Simmer for 2 minutes, then stir in cornstarch slurry. Cook 1-2 minutes until thickened to a syrupy consistency.
Return chicken to the skillet and spoon glaze over, turning to coat. Warm through for 1 minute.
Divide rice among plates. Top each with a glazed chicken breast, a caramelized pineapple ring, and a drizzle of remaining glaze.
Sprinkle with chopped scallions and toasted sesame seeds. Serve immediately.