A PDF page is not automatically a slide layout
PDF records page appearance, while PPTX organizes slides and editable objects. A conversion may place a page image on each slide or attempt to reconstruct text and shapes. The output's editability depends on how the original PDF was created and how content is interpreted.
Open the deck and inspect individual objects before planning substantial edits. A full-page image can be moved or cropped but its text is not separately selectable. If the source contains selectable text, the reconstructed line order may still differ from the original reading sequence.