Orion should launch using the mode (full screen or windowed) that was active when the app was last closed. Currently, Orion always opens in windowed mode even if full screen mode was active when the app was last closed. This requires an additional click to switch to full screen mode.
Safari opens in full screen mode if it was in full screen when the app was last closed (or in windowed mode if it was in window mode) but that doesn't work for Orion (Orion always opens in windowed mode regardless of the mode that was active when the app was closed).