When could a surface raider really divert British power?

Did Admiral Scheer's mission create useful openings for Germany elsewhere?

In theory yes, but its effect was limited in early 1941 because Britain still had substantial forces available; timing was decisive.

A German raider appearing in early 1941 faced a Royal Navy that still had substantial forces available to hunt it. Its mission could divert cruisers and a carrier, but the timing limited the opportunity created elsewhere. The losses accumulated through the rest of 1941 and into 1942 changed that calculation sharply. A comparable raider appearing after those losses, while Britain also faced Japan and Italy, would have imposed a much more serious burden on global force allocation.