From the docs

Difference Viewer: context specific shortcuts
The shortcuts specific to this context are:
Next difference F8  Diff.NextDifference

I want to use the Diff.NextDifference command in the Text Editor context.
I’ve added a global keyboard shortcut but it doesn’t do anything unless the difference viewer is open.

Is there a keyboard shortcut to switch to the Difference Viewer? Tools.DiffFiles again doesn’t do anything.