I would like to offer a few suggestions regarding the database part of LibreNMS.
In my opinion a date_added (timestamp) field on the devices table would be useful for reporting. Currently there is no way to easily find out the exact date when a device was added.
Similarly, an added_by (int) field that would store the id of the user who added the device.
Regarding the MySQL datamodel, I would be very interested in having access to a crow feet diagram and a field description table to facilitate the development of reporting functionalities. Currently I need to do a mix of guesswork, trial and error and digging through the PHP code to discover what does what.