let's forget about
-the weaker CPU
-the Ram being slower and half what the one has
-the fact that a game needs to be able to run in portable mode first, meaning that the real bottlenecks are in the handheld mode. So all we can expect, is a difference in resolution or FPS, but that won't bring the power needed to run for example ME andromeda at 720p 30fps, not without some serious downgrades
I would add that if the dock mode was that much powerful, Splatoon 2 or Zelda would run at 1080p easily. But they aren't.