Please find the sample code below. Thank you for helping me on this

ex:The console.log for data from getCaseRTByDeveloperName:{data: "{"Support":"Id1","Suggestion","Id2"}", error: undefined}.
I am trying to extract the keys returned by Apex (Support, Suggestion)            


--- Apex

public with sharing class CreateCaseHelper {

@AuraEnabled(cacheable=true)    
public static String getCaseRecordTypeDeveloperNameMap(){

    Map<String, Id> psdCaseRTDeveloperNameMap = new Map<String, Id>();

    for(RecordType rt : [Select Id, developername from RecordType 
    where SobjectType = 'Case']){

        psdCaseRTDeveloperNameMap.put(rt.developername, rt.Id);

    }

    return JSON.serialize(psdCaseRTDeveloperNameMap);


}

}

--- LWC HTML

<template>

    Suggestion Case Record TypeId:
    
</template>

---- LWC JS

import { LightningElement, api, track, wire } from "lwc";
import {
  getObjectInfo,
  getPicklistValues,
  getPicklistValuesByRecordType
} from "lightning/uiObjectInfoApi";

import CASE_OBJECT from "@salesforce/schema/Case";

import getCaseRTByDeveloperName from '@salesforce/apex/CreateCaseHelper.getCaseRecordTypeDeveloperNameMap';

export default class CaseTestLWC extends LightningElement {

    @track suggestionCaseRecId = "";


    @wire(getPicklistValuesByRecordType, {
        objectApiName: CASE_OBJECT,
        recordTypeId: "$suggestionCaseRecId"
      }) wiredRecordTypeSuggInfo({ data, error }) {
          if(data){
              console.log("data from getPicklistValuesByRecordType: " , data);
          }
      }
    
    
    @wire(getCaseRTByDeveloperName)
    caseRTByDeveloperName(data, error){
    if(data){
      console.log("data from getCaseRTByDeveloperName:", data);
      
      let p = data;
      for(let i in Object.entries(p)){
        
        var key = Object.entries(p)[i][0];
        var value = Object.entries(p)[i][1];
        console.log('key['+i+']='+key+' '+'value['+i+']='+value);
      }

    }else if(error){
      console.log("Error Occured while geting case record types ---> " + error);
    }
    
    }


}

---- LWC Meta

<?xml version="1.0" encoding="UTF-8"?>
<LightningComponentBundle xmlns="http://soap.sforce.com/2006/04/metadata">
    <apiVersion>48.0</apiVersion>
    <isExposed>true</isExposed>
    <masterLabel>Create Case Test LWC</masterLabel>
    <targets>
        <target>lightning__RecordPage</target>
        <target>lightning__AppPage</target>
        <target>lightning__HomePage</target>
        <target>lightningCommunity__Page</target>
        <target>lightningCommunity__Default</target>
    </targets>
</LightningComponentBundle>