Creating a custom language syntax checker / highlight error in VSCODE

Question

I have a file with some custom syntax, I'd like vscode to highlight keywords and check that the syntax is correct.

sample file:

{
    someLogic: [
        {
            action: "someAction",
            debug: true,
            myQuery: "
        
            declare
                a       number := 5;
                b       number := 7;
                sum     number;

            begin 
                sum := a + b;
                dbms_output.put_line('a + b: ' || sum);
            end;",

            params: ["val", "val2"]
        }
    ]
}

as you can see the file consists of key value pairs where the key is not surrounded by "" and the value may be a plsql code block string. and there could be arrays, objects. It's basically a "relaxed" json parser where the keys is not surrounded by "" and value might not be surrounded either (special case for debug: true) I'd like vscode to highlight syntax / provide autocomplete in the file.

What are the steps to doing so? I'd like this new 'language' to be available globally in vscode.

Thank you.