The free edition of KPT Links for PowerPoint for Mac: linked images, the InDesign way.
It adds a KPT Links Basic tab to PowerPoint with Place Linked (PNG, JPG, TIFF, PSD, HEIC, PDF, AI and SVG, into the shapes you selected or as a new frame), Update Selected (the frame never moves or resizes) and a Links panel that lists every linked image with its state: OK, modified or MISSING.
It installs next to KPT Links ADVANCED without touching it: a different file, a different tab and a different folder. A deck made with Basic is a linked deck to ADVANCED.
The installer asks for your Mac password because PowerPoint reads add-ins from a folder shared by every user of this Mac. No account, no ads, no tracking, nothing is sent anywhere.