Haven’t heard of anything, but honestly wouldn’t be surprised if not, given that most of the unique weapons are downgraded versions of the legendaries in this dlc, or vice versa.
I know that there’s more wall decorations, should stand out nicely in the unlit corners of my dark room on sanctuary.
The new character skin I’ve found is quite nice, though.
DLC4 does indeed have unlockable heads. It also has unlockable skins.
I’ve found a couple of skins.
Where do the heads drop from? Bosses seem to have really awful drop rates, so I’ve not seen much.
I’ve found most of mine by farming B and M.
I found all heads and all emotes while farming Loco.
Hope this helps 
Wait this DLC has drops? Could have fooled me.