A pot of pinto beans, flavored with onions, garlic, and a bit of green chile are fine eating and served with many entrees here in NM. Meat helps, but is not necessary.
If you start with canned pinto beams, saute a chopped onion and a couple of mooshed garlic cloves in vegetable oil over medium heat until the onion is translucent, probably 3 to 5 minutes. Add 1/4 cup chopped green chile, 1/4 tsp cumin seed, 1/4 tsp mexican oregano, and cook for a couple of minutes or until you can smell the toasted cumin. Then dump in two cans (15.5 oz size) of pinto beans and add 1/2 tsp kosher salt. Bring to a simmer. Then transfer this to the smoker and smoke for an hour or so. If at any time you need to add liquid, add vegetable broth. Taste and add salt if necessary.
The time in the smoker will add smoke flavor, but not cook the beans, which are essentially edible after they have been brought to a simmer. By heating the beans up before you put them in the smoker, you are ensuring that the thermal mass of the beans does not pull the smoker temperature down, and that they do not linger in the danger zone.
Meat fat helps the flavor of most everything, particularly beans, but you can make an acceptable pot of beans without meat fat. It is harder though.
If you want to start from dry beans, let me know. I have a recipe for that as well.
Or you could just buy a couple of cans of your favorite vegetarian baked beans from the store, heat it up in a pot and put it in the smoker for an hour or so to get the smoke flavor. Adding some maple syrup, sorghum syrup, or Kentucky Bourbon to the mix helps. All three are based on vegetables, so should be acceptable to vegetarians.
If you want sweeter baked beans, you can use a couple of