The Portkeys HD7H is an affordable, entry-level 7-inch on-camera monitor.
This HDMI-only monitor can take video signals up to 4K30p, is daylight-viewable with a maximum brightness of 1,000nits, and can be easily be powered for hours by a single Sony NP-F battery or externally via its power input port.
Whether you're a beginner or a professional, it has all the necessary monitoring tools.