How to open a PDF presentation in PowerPoint?

Nothing is free and the Canva site wants an email address to proceed with the PDF > PPTX conversion after one drags and drops the PDF onto the site. I would not recommend using an email address that you don't want unsolicited email sent to. I would also expect Canva to limit the quantity of conversions.

When the Canva conversion is done, click the Share button in the upper right corner of the browser window, select Download from that panel, and on the Download page, select the file type as PowerPoint PPTX. The downloaded PowerPoint presentation will have *.pdf.pptx in the filename.

I started with a Sample.pptx presentation that I opened in PowerPoint 16.103.3. I exported it as PDF, and used that PDF for the Canva action. The converted PDF > PPTX was very accurate when the resulting PPTX was reopened in PowerPoint.

If you have access to Adobe Acrobat Pro, it can open a PDF and export to PowerPoint. Might be more accurate than web-based, or other approaches. Unlike MS Word where it can open a PDF directly and convert into a .docx document, PowerPoint was not given that feature for converting PDFs into PowerPoint slides.

There are websites like the free https://www.canva.com/features/pdf-to-ppt-converter/ where you can convert PDF tot PPT. I haven't tried it myself yet. Maybe other members here do have more experience with canva or other websites that provide this possibility.