For example, a $20 La Frite (1GB RAM, AML-S805X-AC) with a $15 (8MB) or $20 (16MB) EMMC 5.x module (for OS) runs upstream Debian ARM port and a vanilla upstream kernel without vendor-specific patches.
I'm struggling very hard to find a reason to buy this board other than the price (which I admit, is nice).
The hardware is much better (reliable) than 'Pi, at the same price range. That's why I used it as an example. Libre Computer completely fucked up the Kickstarter, though; I was/am a backer. Drived off a LOT of developers/users. (Didn't get the EMMC, which was a mistake.) You can find the pinouts in the
schematics and at the
LoverPi forum. Or you can ask Libre Computer directly; they're absolutely not hostile, quite friendly, but .. neglectful.
Now that I think of it, they fucked up the Kickstarter much the way Mnementh described Creality fucking up theirs. (Except Libre Computer didn't get it in retail any sooner, just completely botched the time estimates.)
At the core, it is a very straightforward Amlogic AML-S805X-AC board, so the support matrix at
Linux-Meson fully applies. GPIO Pinctrl, PWM, interrupts etc. are built in to the kernel. For example, GPIO pins are accessible via the standard kernel /dev/gpiochip
N character device(s). So, technically, as long as you can find the Meson docs, you don't actually need any manufacturer specifics except for the schematic. This was also a core point: you are not dependent on the manufacturer support or documentation of the various subsystems; you only need to know what they are, and the community has the rest, because the hardware itself is supported at the kernel level.
If you were to ask me, I'd recommend an
Odroid instead. (I have a HC1 and a C1+.) They have much better documentation, and the user forums are quite active (as in, manufacturer answers questions and takes advice very actively; it's not just us users talking amongst each other). The hardware hasn't failed me yet. I am thinking of getting a
HC4 (to replace my HC1 as a firewall/server), but the price (USD $65 as of now) is higher than 'Pi. The base
C4 (USD $50) matches 'Pi 4 performance, has a rock solid Amlogic S905X3 (see Linux-Meson), and 47 GPIO pins supported in the vanilla kernels, in case you need those.