How to retrieve a value from a JSON using bash?

I have a command in a bash pipeline that returns me a JSON like the follow:

$ aws iot get-registration-code
{
    "registrationCode": "abcd635"
}

I would to have the value abcd635 inside a variable code that I can use somewhere in the code.

//Pseudo code
regCode = aws iot get-registration-code;
code = regCode.registrationCode
do some stuf with the code variable.

Is that a way to achieve this without the use of jq? I think it is because jq is too much for this simple JSON.