Thinly slice white or yellow onion and set aside.
Combine chili powder, garlic powder and paprika in a small bowl and mix well.
Pat bison dry with a paper towel and season both sides with salt and pepper, to taste. Pour about 1/2 of the dry rub mix on one side of the bison, using your hands to spread it around until evenly coated, and use the remaining spices to coat the other side.
Spray slow cooker with nonstick cooking spray, add thinly sliced onions and lightly drizzle with olive oil and season with salt and pepper. Add seasoned bison on top.
Next, add about 24-28 oz of broth, or enough to almost cover the meat with liquid.
Cover with a lid and cook on low for 6-8 hours. (For a 1.5 lb chuck roast, my bison was easily shreddable around the 6 hour mark. Cook time will vary depending on the size of meat.) The proper internal cooking temperature for bison is 160 degrees Fahrenheit.
While bison is cooking, prepare coleslaw. (Coleslaw does not keep very well, so I would suggest making it closer to the time you are planning to serve, or waiting to add wet ingredients until that point.)Use a food processor or grater to shred carrots and apple. Make coleslaw by combining all ingredients in a large bowl, mixing well and store in a covered container in the refrigerator. You will top each slider with about 1/3 cup of prepared coleslaw.
Once bison is ready, use two forks to shred it, then add meat back to the liquid in the slow cooker. Pour in 1/2 cup of barbecue sauce and stir well. Place lid back on the slow cooker and let sit on low for another 30 minutes or so.
Now you are ready to serve! Top each slider bun with about 1/3-1/2 cup of pulled bison meat and top with coleslaw, and any additional toppings such as, barbecue sauce, fried onions, pickles, etc. as desired.
Store any leftover bison in the refrigerator in an airtight container and enjoy within 3 days, or transfer to a freezer-safe container and stick in the freezer to be consumed within 3-6 months. Enjoy!