Kongs are not safe. I would never recommend them.

Nina Ottosson by Outward Hound Dog Brick Interactive Treat Puzzle Dog Toy, Intermediate https://www.amazon.com/dp/B0711Y9XTF/ref=cm_sw_r_apan_i_D4KCY8D4RJDVM4M4DPZF

Pet Zone IQ Treat Ball – Adjustable Dog Treat Dog Ball & Treat Dispensing Dog Toys (Dog Puzzle Toys, Dog Enrichment Toys, and Interactive Dog Toys in One) Great Alternative to Snuffle Mat for Dogs - 3" https://www.amazon.com/dp/B00OZOQN3U/ref=cm_sw_r_apan_i_B3SM8QYJYH6Z2QFDKMPP

Dog Puzzle Toys,Dogs Food Puzzle Feeder Toys for IQ Training & Mental Enrichment,Dog Treat Puzzle(Blue) https://www.amazon.com/dp/B08RY2YRFG/ref=cm_sw_r_apan_i_210V52ECBYE5GY0Q4C2W?_encoding=UTF8&psc=1

Nina Ottosson by Outward Hound Dog Twister Interactive Treat Puzzle Dog Toy, Advanced https://www.amazon.com/dp/B0719Q89X8/ref=cm_sw_r_apan_i_HD3R64Q87VS2B02E092M

I have the IQ Ball, Dog Twister, and the Kong Wobbler. After you teach your dog how the toys works, he'll most likely "solve" them at their hardest settings in about 5-8 minutes. But my dog still gets all of her food through puzzle toys.

Frozen kongs filled with wet dog food are great though. They'll keep my dog busy for about 30 minutes.