So you would like to use iPhone or tablet as an external monitor for filmmaking? The Hollyland Mars X wireless video system has you covered. It has collapsible antennas and a single HDMI in with 1080p resolution. You will be able to connect 3 iOS or Android devices for app monitoring.
The Mars X has a transmissions range of 300ft and 8 frequency channel options that can be used to avoid interference. It has an OLED display to show battery status, frequency channel, video format, and other relevant information.