You've asked for slowcooker recipes...
My husband actually does most of the crockpot cooking around here. He does this one with a homemade barbecue sauce. Sorry, I can't give you the recipe for that, because he can't give me the recipe for that, because he just dumps stuff in and does it by smell every time.
Purchased barbecue sauce usually has lots of additives, but if you learn to make your own it can be free of gluten and other allergens... ours usually has tomato paste, tomato sauce or ketchup, brown sugar and/or honey, vinegar, chili powder, garlic powder, liquid smoke, salt, etc...(Obviously to be GF you'd then have to eat the meat with a fork, rather than on a bun...but we tend to do that sometimes anyway!)
You can also do this with beef brisket.
1 pork shoulder of several pounds (other pieces may work also, but you want one that will shred apart, so not chops or loin) With or without bone is fine.
Put the (thawed) meat in the crockpot, cover it with barbecue sauce (as in, put sauce all over it, not bury it under a lake of sauce!). Cook on high for a few hours. I always like to check in on it about halfway through the day, and if it's cooking fast then switch it to low...but it can go on high for a good 6-8 hours (or on low for 10-12 I would guess).When it is done, get a fork or knife or tongs and pull the meat all apart. Stir it around, add a little more sauce if you like, and let it cook a few more minutes.
Serve on rolls (I used these ones) with mayo and/or barbecue sauce.