Verbatim Portable Touchscreen Monitor 14" USB-C HDMI Full HD 1080p IPS Display with Metal Housing and Adjustable Kick Stand for Laptops and Gaming Consoles

I use a 26400mah PD USB-C battery, which has 1 x USB-C pd 100w and 2x 3.2 USB a ports. I love it, I have 2. I begrudgingly gave one to a friend but I replaced it instantly lol. I have 2 portable USB-C touch screens. One is the espresso and the other is a cheap $250aud one. They both have 2 USB C ports and a HDMI mini. One of the USB C ports is 100w PD pass through.. so I just plug USB-C from the battery to the monitor and USB-C altdp to my s22u. So 1 battery and cable is needed to power the monitor and charge the phone. Of course I can just plug the phone to the monitor with no battery and it will power the monitor. The monitors add about 3 watts of power usage so really you just need to worry about the size battery required to run your phone doing whatever it is your doing for the length of time you want to do it. You will probably have your display off as well so it probably works out to use less power. EDIT: I use an Intel NUC as well with the displays and battery and it works the same, the thunderbolt 4/USB-C DP power the monitor. So again no need for an extra cord or battery. With both batteries my phone could run all day easy depending on what I'm doing, maybe 2. With the NUC I think I get around 2-3 hours of non stop use, video, streaming, coding downloading etc from 1 battery.