The report template functionality currently does not support PowerPoint files. Can you describe the scenario that you would like to have slides generated?
All of those great stats I can automate using the Survey123 Reporting API into word I want to be able to 'present' to a customer. Storymaps and dashboards don't work, as I can't guarantee I'll have sufficient connectivity, nor do they allow me to print something out and send it to the customer as a deliverable. The word report is awesome for being a deliverable, it's just not great to present a word document.