We know the Abwehr was both (1) deep in league with the Nazi Resistance, (2) was nearly useless as an intelligence agency for Hitler, and (3) never got even one agent into Britain that wasn't captured, executed, or turned into a double agent. In addition, they believed hook, line, and sinker, the master work of Agent Garbo.
Especially in the context of D-Day, where the blunders were catastrophic, is it possible that Canaris and crew were deliberately sabotaging the war effort as de-facto British agents or as monarchist double agents?
What, if anything, would be different about the actions of the Abwehr under Canaris's care if he actually had been a British agent or Kaiserite Double Agent?