i would like to find and replace string in json.

Example json:

{
  "app": {
    "value": "ff5aeb05-7a22-46fd"
  },
  "name": {
    "value": "John"
  },
  "surname": {
    "value": "Smith"
  }
}

Only replace “John” or “Smith” to something “XYZ”. Looking for the value of e.g. name. Then replace word after: “value”: “John” to “value”: “XYZ”

This is my proposal but i would like the solution to be generic.

SELECT regexp_replace('{"app":{"value":"ff5aeb05-7a22-46fd"},"name":{"value":"John"},"surname":{"value":"Smith"}}','John','XYZ')
FROM DUAL