There is no official certificate for any service animal. People can train their own or have a professional do it.
As to restraining a dog in a seatbelt, it is easily done with adjustable straps that fit into the seatbelt receiver and fasten to the dog's harness. Available on Amazon for a very reasonable price. I have them for my 11 pound terriers and gave a set to our groomer who transports all her canine clients in her SUV. You don't want even a small dog flying through your car in the event of an accident.
As to restraining a dog in a seatbelt, it is easily done with adjustable straps that fit into the seatbelt receiver and fasten to the dog's harness. Available on Amazon for a very reasonable price. I have them for my 11 pound terriers and gave a set to our groomer who transports all her canine clients in her SUV. You don't want even a small dog flying through your car in the event of an accident.