Oracle PL/SQL Anonymous block equivalent in postgres

Hi ,

Here is the requirements :

1. Development & Support team can ONLY have READ Only ACCESS
to PRODUCTION Database. They will NOT have access to create
stored procedure & functions in the PRODUCTION on the fly.

2. During application support, need to write script which
uses procedural language (IF ELSE, AND , OR, Cursor, Loop etc)
to produce results or identify/fix issues. Number of this kind of
Requests goes in hundreds during Quarter end.

Currently on Oracle as long as you have sqlplus read only access,
you can write PL/SQL block and get the work done.

Since postgres doesn't support procedural language except in
stored objects like procedure/functions, how do I achieve in
postgres without using stored objects. If this is not possible,
then does it make sense to add this requirement into TO-DO list.

Pls advice.

Thanks
Ashok