The only items in the strongbox were my key rewards. I have only been on and voting for two days and have been at both of the last two vote parties. I am not sure exactly how many keys I got and used, but without bonus key rewards (one of which was one of my legendary keys that got me the unpowered flux armour) id guess around 20? I used at least 3 legendary keys total, one was resonant storage blocks, another one, and the flux armour key. I cant remember what the second one was sry. All of these rewards were in the resonant strongbox from the first legendary key reward. I hope that's helpful I cant remember all the stuff that was in it as it was nearly full of blocks of different high value materials I was collecting from the key rewards to start a base.
Thank you for your help!