Paladin oath vs dark gift

The premise of the question is pretty simple.

Can a paladin make a deal with a demonstrably evil entity and keep their oath?

I suppose a vengeance paladin could argue that striking a deal with a lesser evil is in line with their oath, but what about the others? This goes beyond "being cordial with Strahd and biding time".

Party just got to the Amber Temple from the portal room in Castle Ravenloft. I'm considering tying dark gifts to inherently evil acts: sacrificing innocents, murder, etc. I am not sure if that is necessary.

Yeah, I know that some of the gifts have actually powerful drawbacks, but others are just cosmetic.