Instagram website use the same trick you find her (In this case also a guide I wrote):
Add read-only link (If you are unable to complete the steps in the manual).
CMS content excluded - hard to answer without knowing what kind of data you put in those “first/last” cells. One option is to use conditional-visibility:
Create in your collection list extra div with the name of “the first cell” put any content you want - and use if first-cell (Add Checkbox field to your data) show this.
another div/wrapper inside your collection item - for the image/price and so on - and use the same logic (If “the first cell” or the last cell false - show content).