Dear Maeve,
Good day!! I hope you are doing well~
As per the description shared, I understand your concern and to my knowledge, I would like to convey that you can follow the below steps to paste the data in the Excel workbook into the PowerPoint presentation as a link so that the changes you made in the Excel workbook are reflected on the presentation:
Step 1: Keep the presentation and Excel workbook into a folder in the SharePoint Online site.
Step 2: Sync the folder or document library to your File Explorer on the Windows using the OneDrive sync client. (Open the Document Library or the folder where both files are present> Click on the Sync button)
Step 3: Open the Excel workbook and PowerPoint presentation in the synced folder> Select the required content to display in the presentation and copy the selected content using Ctrl + C.
Step 4: Go to the PowerPoint Presentation> Go to the slide> Go to the Home tab> Click on drop-down arrow at the Paste> Paste Special> Paste Link> Microsoft Excel Worksheet Object> Click OK
Apart from the above procedure, there is no any other recommendation in the PowerPoint presentation or Excel workbook to achieve the requirement you are looking and the other alternative can be with the help of the custom Power Automate flow.
If there is any misunderstanding or confusion from our end, we apologize and request you to share the more detailed information which will help us to better understand and guide you further.
Appreciate your patience and understanding. Have a great day!!
Best Regards,
Sophia