Hi Marta! The best way to do this is to store the last_purchased_product and last_viewed_product as custom attributes, possibly custom attribute objects in the user profile. One concern I have with this is that this could possibly take up quite a bit of data points bc every time a product is viewed, that would consume 1 data point. If your team can agree to move forward with logging these data in your user profiles, then it would be pretty simple.
This is also assuming that you only want to show the single most recent product purchased or viewed. If you're hoping to show multiple, then it's not much more complicated; probably just need to use an array to capture the products.
Regarding the grid and the email build, that would be up to your HTML Devs to provide the right email template that you're looking for. Once you have the right template, it's just a matter of inserting the right custom attributes inside your email template.
Another data-sensitive route is to build an API endpoint from your backend that can return the user's most recent product purchased or viewed. If this is created, then you can make a Connected Content call from your emails. This won't consume any data points, so that would be nice, but you'd have to consider how many API calls your endpoint can handle.
Let me know if you have any questions! Attaching my calendly link below if you'd like to chat.
