You will be able to use the Openoffice report designer if you are using an old linux version that still maintains the old version of python-uno library that works for the 2.7 or 2.6 version of python because the new version of python-uno are only for python 3.x, also you will need to use an old version of Openoffice like around 3.3

Also you need to take into account that the old report designer plugin for Openoffice is to generate the RML format of reports that is actually deprecated.

I plan to build an standalone report designer for Odoo for the future but right now it's very time consuming and costly.