How about
Odroid N2L with eMMC, based on Amlogic S922X SoC?
Or
Odroid M1 based on Rockchip RK3568 SoC, with an eMMC module?
Amlogic, Samsung (Exynos), and Rockchip all push their kernel changes upstream to vanilla kernels, so you're not dependant on what the vendor provides.
I do not personally have either, but have been looking at both. I do have some of the older ones (C1+, C2, HC1), and have had no issues in Linux with them, and I am somewhat familiar with both Amlogic SoCs and Mali GPUs.
(Specifically, I've been looking at both the
N2L 4GByte with the
64GByte eMMC module for computation intensive stuff; and the
Odroid M1 with a
16GByte eMMC module for media server type stuff.)
In particular, the Odroid M1 consumes only 0.06 watts (60mW, 5mA @ 12VDC) when suspended. You will want to use an eMMC module for the core OS, even if you use a SATA SSD or a NVMe/PCIe M.2 2280 SSD card, to reduce boot times by bypassing PetitBoot.
For Odroid N2L, the eMMC module will be your boot and storage media, although you can use an USB 3 hard drive (or USB3 to SATA adapter) for external media.
While 1920x720 is not a native HDMI mode, it can be supported by
setting the display mode using a
custom HDMI/DVI modeset. You do need the display module timings (or EDID data) to construct a suitable modeline, but that's all.
Moreover, you can use
device tree overlays using the same mechanism to set up any SPI, I2C, PWM, or GPIO pins on the
2×20 expansion connector on N2L or
M1. You also probably want to set a custom
bootlogo, since that's shown during bootup and wakeup from hibernation.
In any case, if you decide to go for an Odroid, do check both
wiki.odroid.com and
forum.odroid.com first, for the board. Consider even registering, and asking there (on the proper sub-forum, possibly
Odroid M1 > hardware and peripherals) before buying. A link to the display module or its EDID information (timings) will be handy there.
A completely different approach would be to use (a custom) Android device instead of a Linux distribution. The TV boxes (using e.g. Rockchip SoCs) have good hardware video decoding, but usually run from a ramdisk, and cannot suspend (due to lack of RAM) or hibernate (due to lack of storage). Some of them boot rather quick, though. Of course, Odroid M1 has images available for both Linux and Android, and you can brew your own for both (although it is quite a steep learning curve; so better start with the provided system images).
All things considered, although I'm only a hobbyist who never does automotive stuff, I'd carefully consider Odroid M1, and the 16GByte (or larger) eMMC module.