This is line in the template you would need to override in your theme https://github.com/magento/magento2/blob/2.2-develop/app/code/Magento/Catalog/view/frontend/template...
Instead of outputting the product actions, you will want to check if the product has options, and if not then don't show the add to cart and instead link to the product page.
I haven't tested but there's probably still a $_product->hasOptions() function that you can use to test.
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