There are several keyboard shortcuts available in MapTiler Desktop.
Right / Left or PageDown / PageUp keys - Continue / Back buttons
Ctrl + O (Cmd + O) - Add / Open input file
Delete - Remove file from the list
Ctrl + N (Cmd + N) - New project [MapTiler Pro]
Ctrl + S (Cmd + S) - Save project [MapTiler Pro]
Ctrl + Q (Cmd + Q) - Quit application