libreoffice-impress (for some distros, e.g. ALT, Arch, Slackware, there's only an integrated package libreoffice for the full suite). Also, okular-backend-odp¹ allows viewing them in Okular.

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¹ — in a Debian-based distro, in other distros it may be named differently, e.g. calligra-okular-odpgenerator in Fedora, calligra-okular-pptx in OpenMandriva, or be part of another package, e.g. calligra-okular-generators in ALT, calligra-stage in Mageia, calligra-extras-okular in OpenSUSE, etc.

Hi shruggy, would these work with Mint 20?

Why not? Try it.

Hi Shruggy, just wanted to say thanks, L.O. Impress works great! Merry Christmas!

First, you can consider opening PowerPoint presentations online, for example, using services like SlideOnline to publish PowerPoint and PDF. However, if you need to edit PowerPoint on Linux, you can choose to use OpenOffice Impress LibreOffice. Both are open source alternatives to PowerPoint that can be used on Linux. You should understand in advance that opening a PowerPoint presentation with OpenOffice or Libre Office may not achieve the same results or appearance as opening in PowerPoint, especially for slide show transitions, animations, using PowerPoint templates or using custom graphics. However, you can get the content of the presentation and just view the presentation.

Yes, and that's what the OP went with before they closed this thread. And this is the second thread where you post commercial software to a question that's already been answered.