Well well, who knew. But I found it.
Basically, the solution gives me:
- Dual 4-lane MIPI-DSI D-PHY 1.2
or 2x MIPI-DSI 4-lane, 60fps, up to 4096×2160 (dual port) support.
- HDMI 2.0 out/in. Support for 4K 60Hz streaming capture and playback.
- Supports: Linux Kernal 4.4 aka Ubuntu 16.04 (LTS) Xenial Xerus.
- Support audio: 24bit/192kHz FLAC playback
- Offering seamless connectivity to external memory, sensors, and a host of other peripheral devices via the comprehensive list of configurable IO.
I would say that this is exactly what I am looking for. Within a 170mm x 170mm [6.69 x 6.69 in] physical size (for the board)
This mean that the computer and display is less than $800 usd and well within my $1500 total budget - and for that I get 4K@60Hz media hub projector - a non existing product.