[Zubersoft]

Unfortunately, that's just not possible. The pedal command is just a key command (the same as if you pressed a key on a computer keyboard). That key command is going to be issued to the application with focus. C# UWP apps can't install things like global key hooks to capture key commands issued to other applications (that's usually viewed as a big security risk as it can be used for key logging and such).  So I can't change the way the OS works.

One thing you could try is using a MIDI device with MIDI actions in MobileSheets to change pages. I believe MobileSheets will process those regardless of focus. You'd need a pedal capable of sending MIDI messages though, and I'm not sure if that's readily available.

Mike