Heat a large skillet over medium heat and add the ground meat, breaking it apart with a spatula until browned and cooked through, about 5-7 minutes. Transfer the meat to the slow cooker.
In the same skillet, add a splash of oil if needed and sauté the chopped onion until translucent and fragrant, around 3-4 minutes. Transfer the onions to the slow cooker.
Add the minced garlic to the skillet and cook for about 30 seconds until aromatic, then transfer to the slow cooker.
Stir the cubed pumpkin, drained beans, diced tomatoes with juice, chili powder, smoked paprika, cayenne (if using), and broth into the slow cooker with the meat, onions, and garlic.
Season with salt and pepper, then cover and cook on low for about 1 hour, stirring occasionally until the pumpkin is tender and flavors meld.
Check the chili and adjust seasoning as needed. If you want a thicker consistency, uncover and simmer on high for an additional 10-15 minutes until slightly reduced.
Serve the pumpkin chili hot, garnished with fresh herbs or shredded cheese if desired, and enjoy its velvety, hearty texture.