Yes green tripe is good stuff. I used to feed this frozen green tripe from Blue Ridge Beef --

https://blueridgebeef.com/products/green-tripe

They were out of it for awhile, they said it was all going to China. But they have it again. If you are on the east coast, the Blue Ridge Beef company has quality raw feeds for dogs. I also use their Puppy Mix, it has a good blend of raw meats, organs and bones.