I'm Daryoush, on the winning Guru team! :)
I have two recommendations to search in the Shopify admin for any products missing images:
The first solution is to export your product list by going into "Products" -> three dots -> "Export" which will provide you with the product CSV file Shopify Doc. You can use this to view the "Image Src" and "Variant Image" columns, if there is no image URL, then there are no images.
The second solution is to use an app, such as the awesome Image Manager to quickly sort through products and view/upload product images. Another useful app is Bulk Image Edit, but I would use the Image Manager app first, because it's better suited for this.
I hope this helps, have a lovely day!
Ah once again, Shopify wanting to sell the car seats separately. I really wish this idiotic system wasn't so a la carte and actually had features built into it that made sense. I too am in the same boat with 35K some item entries and I'm having to skim through 50 freaking items at a time. So annoying.