Is there a way to sort or filter products based on the size/dimensions of the product images?
I want to replace smaller-sized images with larger versions, and would like to be able to filter or sort the products based on the existing images in the listings so I can determine which ones have smaller images that need replaced.
Your images are lazyloaded so probably it's not practical to do this. Shopify doesn't offer a native way of filtering like this so you'd probably need to build a custom script that requests all images at their maximum size and returns some data based on that.
You could do this with the Product Image viewer on the Sheet Master free version https://apps.shopify.com/sheet-master - the report includes image height & width as well as an ability to view the original scale of the image. Here's a video demo
Here's a blog post on the product image viewer, let me know if you need any customization.