I have great success with these dehydrated liver treats. Also read a useful blog post that said you could blitz these up into powder and sprinkle them on kibble to trick your dog into thinking they're higher value than they actually are.
Yeah it comes in buckets or Trader Joes has their own brand in smaller bags. Most dogs love it since beef liver is a very strong flavor and dried out it is pretty irresistible.
https://www.amazon.com/Stewart-Freeze-Dried-Treats-Liver/dp/B000255OIG
These are the ones we use!
https://www.amazon.com/dp/B000255OIG?psc=1&ref=ppx_pop_dt_b_asin_image