The most simple way  is to redirect your I/O to a TCPport where another job provides you with the expected input:
#1) have a listener:  (any port, I use 7777 for the example)

#2) at your report side all you have to do is

here the listener sits on the same machine but it could be any reachable IP-address.
the only critical point is if your program fiddles around changing $IO

it is not possible within the same class as you break the uniqueness of names.

But if you have class A1 with Method MX(....)  
you can create class A2 Extends A1 and overload Method MX as you like or need.
You still can call MX of class A1 from class A2 using ##super()

All with the assumption that neither class A1 nor Method MX is FINAL

Use method FindAt for %Library.GlobalCharacterStream

https://cedocs.intersystems.com/latest/csp/documatic/%25CSP.Documatic.cls?PAGE=CLASS&LIBRARY=%25SYS&CLASSNAME=%25Stream.Object#FindAt

see this article ECP between IRIS and Caché / Ensemble

Exactly!

here is the example Defining a JDBC Connection URL

   jdbc:IRIS://<host>:<port>/<namespace>

where the parameters are defined as follows:

• host — IP address or Fully Qualified Domain Name (FQDN). For example, both 127.0.0.1 and localhost indicate the local machine.
• port — TCP port number on which the InterSystems IRIS SuperServer is listening. The default is 51773 (or the first available number higher than that if more than one instance of InterSystems IRIS is installed — see DefaultPort in the Configuration Parameter File Reference).
• namespace — InterSystems IRIS namespace to be accessed.

I'm not aware that this is available at SQL / DDL level 

You can set the default collation for all globals in a database.

or specific for an individual global before using it. 

The available collations have to be added here

I see 4 critical points to check:

• if customerID is autogenerated or calculated you can't  insert to it or update it
• if customerName has some constraints like UNIQUE or fails some other formal checking
• if the (existing) record is locked by some application running in parallel
• if some access rights block you  

what you are looking for is called global indirection

https://docs.intersystems.com/iris20201/csp/docbook/DocBook.UI.Page.cls?KEY=GGBL_using#GGBL_using_indirect

and so on

Almost right!
not $order but the related global blocks are cached in global buffers.
large global buffers improve performance but they have to be loaded first.
and disk access is the slowest part in your machine (except network)

so at 1st access, you load the buffers and that might be slow.
any further access uses the loaded buffers

There is a JDBC driver to PostgreSQL available.
Using that drive you define an SQL Gateway for your PostgreSQL  and establish a link for your tables:
The projection can be accessed as if was a table in Caché.
Details & HowTo here: https://cedocs.intersystems.com/latest/csp/docbook/DocBook.UI.Page.cls?KEY=GSQL_gateway

just tried. the link leads you to :
https://openexchange.intersystems.com/package/Simple-remote-server-control
there is the link to GitHub

You might be inspired by this:

https://community.intersystems.com/post/simple-remote-server-control

In principle, a job is hanging around waiting for orders. Like a cab waiting for a drive.
 

try it without  "CONSTRAINT TestePK PRIMARY KEY (ID)"
and without "ID INT NOT NULL, " 
so you get an autoincremented unique ID by default

This option 
https://community.intersystems.com/post/terminal-multi-line-option
or the extended one with editor support  
https://community.intersystems.com/post/terminal-multi-line-command-editor
could be useful.

Studio is an integrated part of Caché, Ensemble, IRIS, ... and part of any installation kit for Windows

https://docs.intersystems.com/iris20201/csp/docbook/DocBook.UI.Page.cls?KEY=GSTD
 

In studio you open the class and click the class attribute in the inspector

to edit a table by DDL the corresponding class hat to be DDL allowed.

DdlAllowed - Caché & Ensemble 2018.1.3 — 2018.1.4
 

FIXED !

I have implemented an extension to %ZJSON.Generator to fix missing JSONTYPE

Standard Caché data types don't have a parameter JSONTYPE (!!) so everthing is set to (quoted) "string".
Especially numbers and boolean data must not be in quotes. 
       e.g  ....."NUMfield":124, "TrueFalse":true, ....  
instead of  ....."NUMfield":"124", "TrueFalse":"true", .... 

this extension bypasses the missing parameter for these standard data types as indicated in %ZJSON.Adaptor
/// number = %BigInt, %Currency, %Decimal, %Double, %Float, %Integer, %Numeric, %SmallInt, %TinyInt
/// boolean = %Boolean

For customized data classes it is easy to add  Parameter JSONTYPE=". . . ."
But changing sometihng in SYSLIB is a clear NO-NO to me.   ( though it might have been easier)

The extended version of %ZJSON.Generator is here:  
https://github.com/rcemper/Backport-JSON.-to-Cach-/blob/master/MissingJSONTYPE.xml

I didn't meet that.

Basically it's %String or a %Stream based on size.
I'd suggest having a private data type.
This allows you also to have all tricky LogicalToODBC, .... under control. (and no MAXLEN for %String)
And mapping it to %ALL or naming it %ZstringJSON or similar makes it public and update-restistant 

Some more findings what happens:
The output methods are code generated. And the generator just uses JSONTYPE from the data type class.
That means that even as the property parameter is available in Studio, ... you can't change it.

example: Property bool as %Boolean (JSONTYPE="string")  is just ignored  and you see ,"bool":false

This means: JSONTYPE is frozen in the data type class
Bringing Parameter JSONTYPE into the class (e.g, by %ZJSON.Adaptor) has no influence to the Generator 

To achieve the expected result you require a customized data class as suggested by  @Timothy Leavitt 

Out of 25 only these 7 6  classes are affected the rest is string which is default anyhow.

boolean %Library.Boolean.cls(JSONTYPE): Parameter JSONTYPE 
number  %Library.Currency.cls(JSONTYPE): Parameter JSONTYPE 
number  %Library.Decimal.cls(JSONTYPE): Parameter JSONTYPE 
number  %Library.Float.cls(JSONTYPE): Parameter JSONTYPE 
number  %Library.Integer.cls(JSONTYPE): Parameter JSONTYPE 
number  %Library.Numeric.cls(JSONTYPE): Parameter JSONTYPE 
number  %Library.PosixTime.cls(JSONTYPE): Parameter JSONTYPE  not in Caché