Yes, you can bulk upload the Individual Product Alerts, using a csv file.

You just need to export the products from shopify dashboard. Keep only those products in file, you want to set alerts on.

Then make CSV file format as shown below:

Product Title, SKU, Inventory Threshold

Refer this video explaining the steps how to bulk upload the product alerts.

Even if you can share the file exported from shopify, with products/variants and their respective alert levels, we shall correct the format and upload the alerts for you.