Hmm, considering it’s never been my goal... I’d have to say perhaps a minute amount of condensed milk, abc isn’t too sweet IMO, any banana creams you’ve found to not be (too) sweet, I haven’t tried my cream cheese mix yet but it might work well, vanilla bean or stronger vanillas can kill sweet sometimes, maybe a coconut cream, FLV or Hang Cream, FA Fresh cream, TFA Dairy Milk, TFA Greek Yogurt or other yogurts, less sweet Irish creams, TFA Malted Milk?, INW Nugat or nougats in general, FE Oak Milk...
Others which may or may not help: I know you’ve tried some of these... Wondering about brie cheese, taro or sweet potato, boozy, citric acid, INW peanut, cocoa, toast, crescent rolls, yeasty flavors, Bitter Wizard, Trimethyl Pyrazine, MTS
vape Wizard, earthy tobaccos such as Hangsen Indian
Wish I had more to offer in this area!