Structure
Windows RDP -> Android Phone
Linux SSH -> Android Phone
Android Phone -> Hub -> Screen (Type-C DP)
Android Phone -> Hub -> USB Disks
Charger (PD) -> Hub -> Android Phone
Points
Android Phone must run LineageOS or other AOSP-like system.
Android Phone touchable screen as desktop mode's mouse/touchpad.
Android Phone heat: A lift-off 1cm² area on the back, which lifts up in desktop mode to allow the heatpipes to touch the SOC's shield.
Desktop experience: Use Kiwi browser (Chromium) on Android, enable desktop mode.
Software Development: Use VSCode remote web, extension host on Linux, UI on Kiwi browser, use SSH tunnel.
Other GUI App: Use Windows RDP. Don't use Linux desktop.
Connect other devices that needs high permission, like writing bootable USB disk, or flush another Android Phone: Unsolved.
Some Android Phone doesn't supports DP output: Unsolved.
Why
It's a "multiplex-aholic" thinking that want to multiplex everything.
Like, I share Windows and Linux host with others, the only exclusive client is my Android Phone.
Multiplex even my Android Phone, uses it as both a normal phone and a compute unit of thin-client, and a mouse/touchpad.
It is also a kind of extreme case of the opposite of the "multi-client" advocated by many manufacturers nowadays. Certainly, manufacturers want to sell more clients, but in this draft, use mono-client instead.