It's odd that I have to go to a completely different area of the Shopify admin to enter the serial numbers and I can't do so from my main orders screen where I'd be generating shipping labels and doing the rest of my fulfillment process. Also, the serial numbers don't come through the Shopify webhooks at all so I can't use them in my outside system.
Thank you for the review. I understand your frustration.
Unfortunately, Shopify admin pages, such as the Orders screen, are not editable by 3rd party apps such as Serializer. Additionally, 3rd party apps cannot control the data that comes through the Shopify webhooks. However, the serial numbers saved via the app could be accessed by an external system as they are available in the Shopify order metafield - more details in the app's documentation. Please email me if you need any help.