You're asking 2 questions.
>>I want to enable only objects in ORDS and not the entire schema. how do I do that?.
Yes, it's a two step process.
First, you enable the SCHEMA. This allows:
- ords_public_user to proxy connect to said schema to run whatever sql/plsql associated with the RESTful Service or AUTO code paths
- for REST Services to be defined for said schema
- for tables, views, PL/SQL objects to be 'auto' enabled
Once this is done, you can then REST enable one or more schema objects. Enabling a schema does NOT auto enable everything in that schema.
>>Is there a way to enable objects in ORDS for GET methods?.
Yes. If you AUTO REST enable a table or a view, you will allow for GET requests to said objects via their URI's, /schema/table/
However, you'll also get a DELETE, POST, and PUT.
If you only want a GET, then you'll need to code your own RESTful Service, add the GET handler, and supply the code.
you can also have a look here, to better unterstand what is REST enable SQL and what is when we enable a SCHEMA for REST