Invoke REST APIs from within Oracle database with APEX components

Currently we have some custom integrations between our Oracle EBS (R12, database 12c)  and other cloud-based systems such as travel system Concur and HR/Payroll system Ultipro to bring data into Oracle EBS from those system via Oracle Integration Cloud (OIC), The center pieces of OIC we are using are their cloud based connectors/adapters, we use specific OIC adapters for those systems to connect to those data services in the cloud and invoke their APIs to retrieve data, transfer to Oracle and process them.  The response data from the REST API calls  are JSON data.

As an alternative solution using OIC, we are also thinking of developing custom connectors/adapters for some integrations, Based on some Oracle cloud documents, it seems JSON components/packages in Oracle database are required to handle JSON data pulled from calling other system’s cloud-based APIs, and Oracle JSON components are part of APEX. I have no problem of invoking those REST APIs (such as Ultipro APIs) and get JSON response data using REST clients(such as Chrome native ARC, Insomnia, SOAP UI etc..), but I need some utilities such JSON packages inside Oracle database to handle those JSON data . My first question