Apparently there is no method other than manual adding it once html is exported to add custom code INSIDE the opening body tag? Example:
Are you talking about adding it right after the opening <body> tag? You can always include an Embed element at the very top of your Navigator panel and it will include it before any other elements within the body itself.
You can add custom code before the </body> tag either per page (in the Page Settings) or per project (in the Project Settings) 
No. Inside the opening body tag. Appears it did not include my example I pasted. Will try it this way without the <> and see if it works: body data-region=“{examplecode}” data-channelcode="{examplecode}
You can add data attributes to any element natively inside the Designer — although keep in mind there are certain values that Webflow reserves:
If you need to include a value that isn’t allowed, you can always use a bit of javascript like the following:
<script>
const el = document.querySelector('body');
el.setAttribute('data-region', 'value');
</script>
Yeah, for sure. Thanks for all that. But too much. Will be easier to just input in manually after I export the code and before uploading it to the webserver.
No worries! Definitely don’t want you to do anything you’re not comfortable with but I’d recommend considering minimizing your efforts after exporting since that will almost always be more cumbersome than working within Webflow as much as possible.
Good luck with the project 