Prius 'Delivery July'

Are you in the UK too? Mine is the same. As a compromise I'm using the the multi-information display (the top screen next to the speedometer) to display the turn signals. This is a much better location to see at a glance than the bottom left corner of the nav screen.

(If you haven't found this option yet, it is on the option that displays a compass as default. Scroll down from the compass with the nav operating and it gives turn directions on the multi-information display)