Re:choice of display, I'm betting it's for power saving. If you need a better display you can use the HDMI port or DisplayPort USB-C port and just hook it right up to a monitor/TV
I'm guessing it'll have a similar phone app to the Zero. I quite often use that, sometimes foe stealth so i can have the FZ in my pocket and look like I'm doomscrolling and not sniffing the airwaves, and sometimes just because almost 60 year old eyes have a better time using my phone screen instead of the tiny/grainy FZ one.
The Flipper Zero's screen is transflective, I suspect this one is the same. While this technology is possible on larger color displays, it is more common to find these manufactured as small grey-scale screens. They're ideal for battery operated devices because of their low power requirements -- they are legible with the backlight entirely off as long as there is light in the room.
Grayscale displays have no subpixels (or just one, depends how you view it) which should allow for more light from the backlight to pass through compared to a color display, thus reducing energy needs for a given brightness.
