Hi everyone. Not sure if this is something that people already know, but here we go anyway. I've just experimented a little and have found that you can obtain career reward items that you usually would not be able to - with no cheats or mods!
My method:
1 - Go into Manage Worlds and pick an empty lot
2 - Open up Styled Rooms in Build Buy Mode and choose the Heart of Darkness room (which would otherwise require reaching Level 10 of the Secret Agent career in the Villain branch)
3 - Select and then save the room to My Library
4 - Go back to my played family and back into Build Buy Mode, into My Library, and then simply place the room into my house (or rather, on the roof)
Unfortunately, a quick test afterward has shown that while I can now have the items within the room without ever being in the corresponding career (both of my Sims have only been Tech Gurus in this save, 1 in either branch), I can't clone them in BBM (PS4: Triangle button while hovering over an item). However, I'm still able to have and enjoy the items and move them into other rooms.