I have been curious about where the shards are at. I feel like based on Adolin's fight with the Parshendi Stormforms the plate will be important for the non radiants.
I am also of the belief that the plate is a fabrial that is attuned to the specific radiants originally, feeding off their lvl 5 stormlight at a super efficient level. So the plate might be recreatable by modern artifabrians with enough reverse engineering and a lvl 5 radiant.
Attached is a word doc with my work so far, including some notes and reference pages. (I hope it works)
Feel free to rip it apart
Shards.docx
Shards.docx