If you do not have any leftover tri-tip or brisket stated in the Slower Cooker Cowboy Beans, you can easily sub in pulled chicken, pork, or jackfruit. Also, leftover carne asada and or carnitas would be excellent as well. I have seen other recipes that use ham, chorizo, and soyrizo—of course, using the pre-cook versions in the meat section work very well.
These beans are easily veganized. You can sub in your favorite plant-based meat substitutes or omit the meat altogether. If you do not use any replacement, be sure to add smokey elements such as smoked paprika, liquid smoke, and or chipotles. Diced mushrooms or mushroom powder can provide hardiness.