You have already got a suggestion to make a PDF. Illustrator opens and edits PDFs, so at least it works. An unfortunate thing with PDFs is that there can be numerous clipping masks which must be released + deleted and groupings which must be ungrouped.
Another possibility is to save the presentation as *.emf (=Enhanced Windows Metafile). Each slide of a presentation will be saved automatically as a separate EMF to a single folder.
EMFs can be opened in Illustrator. A single ungrouping makes the objects free. Texts and paths stay editable.
One surprise is waiting: If a filled shape in PPt has an edge stroke Illustrator will generate 2 separate shapes: the edge and the fill. That happens also with PDF exports or if you cut and paste from PPt to Illustrator.
Charts will generate more surprises. That happens also if a chart is made in Excel. They are decorated with complex shapes which have grown more complex by every new MS Office release. Even EMF placed or opened in Illustrator can contain multi-level clipping masks and groups. Separate lines can be bunched to compound paths. Some of the lines can be actually filled areas which make stylizing (=simplifying, recoloring with style fitting colors, often CMYK) very tiresome. Some chart styles are rendered to bitmap images which are uneditable. I have kept alive nearly 2 decades old MS Office 2003 only to have simple to edit charts.