Combine the rice and vegetable broth in a large saucepan, bring the mixture to a boil, then lower the heat to a simmer and cover for 35-40 minutes, cooking until the broth is completely absorbed. (Alternatively, you can use half the broth and cook the rice blend in the Instant Pot at high pressure for 25 minutes, with a 10 minute natural release.)
While the rice is cooking, melt the olive oil in a large deep skillet over medium heat and saute the onion and celery until tender, about 8 minutes. Add in the garlic, mushrooms, sage, thyme, and salt, and saute another 8 to 10 minutes, until the mushrooms are tender.
Combine the cooked rice and mushroom mixture, and stir in the apple, cranberries, and pecans, if using. Adjust any seasoning to taste, and serve warm.
Leftovers can be stored in the fridge in a sealed container for up to 3 days.