My name is Ardiane, a Guru here at Shopify!
That's an interesting question! :-) You should be able to do that using our Bulk Editor by going into your Products section:
Once you have selected ALL of your products, you would just click 'Edit products.' You will then be brought to this page:
You'll see a new field appear for Pinterest and all you would need to do is make sure that the products are visible in Pinterest like the screenshot below:
Once you've made sure that all of your products are on Pinterest, this will automatically publish them and you can see products that have been successfully published and which products need to be fixed due to errors. Make sure you review Pinterest's product requirements here - Review Pinterest's product requirements.
I hope that helps and it clears it up for you! :-) Have a great day!