Hello I am working on a small project that willl require a monitor to be powered off a battery pack and accept either a hdmi to dvi connector I have found some monitors but they don't seem to support hdmi or dvi and only output over usb3
I have one of these. The quality is fairly mediocre and I really wish I had a higher resolution, but it works reliably and was cheap. I bought this 2 years ago so look for more updated models. Just searching on Amazon for "portable monitor" brings up some better options than what I purchased.
If you have an iPad around you can try an app called Duet. It allows the iPad's display to be a secondary display for whatever you want and I think is also touchscreen enabled. I know the app costs 20$ but I guess you can't find a better secondary monitor for that.