Some current Android devices that have USB-C 3.1+ and support dp-alt-mode (USB-C to HDMI) will detect when an external display is connected and provide a full extended desktop. [0]

You can connect mouse, keyboard, and display to the Android device through an unpowered USB-C hub that offers the respective ports. Battery life depends on the make/model of Android device.

I have a Motorola phone and the experience is very nice.

[0] _ https://uperfect.com/blogs/wikimonitor/list-of-smartphones-w...

>Although DisplayPort functionality was disabled at a hardware level on Google Pixel 7 and previous models, Mishaal Rahman discovered that it is only locked at a software level on the Google Pixel 8. It is possible to enable display output on a rooted Pixel 8 with the following shell command with adb.

It works perfectly with GrapheneOS as of Pixel 8 and newer.