Generating images for web from .psd file

I am trying to make a website that has custom t-shirts.

I currently have a photoshop mockup with two smart objects that need to be edited in order to create the custom image of the t-shirt.

I am trying to understand the possibility of using the .psd file that I created to generate the image when the user inserts the images to place on the t-shirt (front and back).

Searching around the internet, I couldn't find anything to help me understand neither if it is possible nor a better way of doing so.

I found this example that could explain my intentions: https://printify.com/app/editor/6/29?g=v2