Make al pastor spice paste: Heat 1 tbsp. oil in a medium saucepan over medium-high heat. Add garlic and cook, turning occasionally, until lightly browned, about 1 minute. Stir in oregano, cumin, pepper, and cloves and cook until fragrant, about 30 seconds. Immediately scrape into a bowl.
Wipe out pan and add another 1 tbsp. oil. Add chiles and cook, stirring, until blistered in spots, about 30 seconds. Add pineapple juice, vinegar, and achiote paste and bring to a boil (add 1-2 tbsp. water if needed to loosen paste). Stir in garlic and spices. Remove from heat and let stand 5 minutes.
Transfer chile mixture to a blender, add 1 tsp. salt, and blend until smooth. Season with salt to taste.
Set aside 5 of the 8 pineapple wedges for another use if you like. Rub about 3 tbsp. pastor marinade all over remaining wedges and slide them into a resealable plastic bag. Chill overnight.
Preheat oven to 350°. Line a sheet pan with parchment and set pineapple wedges on top. Wipe off any excess marinate and drizzle lightly with canola oil, turning to coat. Roast pineapple until edges start to brown and crisp, 35 to 40 minutes. Let wedges cool, then cut into ½-in. dice.
Mix pineapple with Pico de Gallo ingredients in a bowl and season to taste with additional chile, lime juice, and salt.
* Find brick-red achiote paste, made mainly from pulverized annatto seeds, at Latino markets.