Across about 90ish mission wins, I received 2 purple guns as Psyker, 1 legendary curio (With +XP %), and a slew of whites. Both purples were earned in the low levels, 8-14ish.
The legendary curio was at 30. In fact the only legendaries my friends have earned were at 30 and were curios.
Tangentially related, the weekly currency shop is bugged but I’m not sure in which way. Mine rotates every 24 hours, meaning there’s a 4/50ish chance of getting something useful. So once every two months or so. My friends rotates every hour which seems much more reasonable.