Is it possible to create a custom page in a suite let with this sort of structure? (Photo is from NetSuite docs)

A suitelet can output any html

Thanks for reply. I'm aware that you can output any html. I suppose what I'm really asking is if this can be achieved with the NetSuite serverWidget module?

Yes, output an Inline HTML field on a form and populate the value of the field with any HTML you want. That way, you get the NetSuite UI and any HTML you want underneath. Using this method, I have done pretty much the same thing as in your screenshot in a recent project.