Hi,
Can you explain what you mean with the "backend GUI" ?
For the moment, the serial listing is not implemented in HikaSerial, so it has to be coded. You can modify some HikaShop or HikaSerial views in order to add the serial listing. But I do not see the right existing view for it.
It is possible to add some content into the joomla user profile view. We already do it in HikaShop in order to display the user custom fields, it uses a system plugin. The same technique could be used in order to add some HTML content in the page.
After that, you can create new views but it would require to modify a existing controller (or to create a new controller), at this moment, depending on the Joomla version, you could loose your modification by updating HikaSerial. At this moment, the best would be to include your modification directly in HikaSerial.
Regards,