debian+phosh running on PinePhone

[a-wai]

I'm having trouble with the power button, I can't seem to reliably turn my BraveHeart on, is there a document that describes how the button is supposed to work? I'm thinking about adding code (probably to uboot) to turn on the LED and maybe other points in the startup process to provide some feedback.

Sure, for the next image I modified the u-boot script to light up the LED, but it still happens a bit late, I'll see to enabling it earlier.
At the moment, the best way to make sure the phone is booting is to connect a serial adapter cable to the headphone jack and monitor the UART output, but early-boot visual feedback is being worked on

BUT unfortunatelly there is not at all information and details about PinePhone. Now... Where we should looking for details of specification, or even correctly comparing PinePhone DTS with any other A64 Allwinner chip and so on?

I'm not sure to understand what's your point here ?
The dts provided by Pine64 looks perfectly fine to me, and enables most components (I already got the sound, modem and graphics acceleration working for the next image release)
There are also a bunch of details, including the phone schematics, on the wiki.