My website promotes rare goods that I don't own.
I mean, I own and resell only the 20% of the goods I am advertising.
I made my website homepage using only 1 collection from Shopify, so I need to change the add to cart button to an hyperlink that redirect my customers to other sellers websites and, let say every 4 or 5 items I will post an item that I own and only at that point I will need the add to cart button.
Is it possible or I am completely wrong?
Yes, It is possible to do it. It would require custom coding and probably hire Shopify developer. Contact me if you need my help.