Heat the olive oil in a large pot over medium heat. Add the diced onion and cook until it softens, about 5 minutes. Stir in the minced garlic and cook for 1 minute more.
Add the chopped sage and thyme leaves to the pot. Stir for 30 seconds until the herbs become fragrant.
Pour in the pumpkin puree, pinto beans, vegetable broth, and coconut milk. Stir everything together until the pumpkin is fully mixed into the liquid.
Bring the stew to a gentle simmer. Cook uncovered for 15 minutes, stirring occasionally, so the flavors combine and the mixture thickens slightly.
Use an immersion blender to puree about half the stew directly in the pot, leaving some beans and pumpkin pieces intact for texture. If you do not have an immersion blender, transfer 2 cups to a regular blender, puree, and return it to the pot.
Taste and season with salt and black pepper. Simmer for 2 more minutes, then remove from heat.