The letterly bubble rarely appears even though it has granted all the access it needs. I have used whispr flow before and love it. I thought this looked promising. Support has been non responsive.
EDIT The correct settings is to turn the letterly shortcut on as well. then the shortcut can enable the letterly bubble . This means that the bubble does not appear immediately and automatically when you activate the text box, so its a two step process (not like in whispr flow)