Ciao Fabio, hi Fabio,
many thanks for your clear explanation about boot flow sequence.
Well, I really would never go back to android unless something with LibreElec flashing goes wrong and I need to unbrick the device.
I've learnt (and you confirmed this too) that cause this great variety of devices it's quite hard to develop a firmware that suits all situations and, for example, I have experienced that I can boot from MultiTool only in presence of both sdcard and usb stick (quite unusual, isn't it ?).
The only backup I have right now is partitions backup taken with single ADB commands such as "dd if=/dev/block/rknand_system of=/path_to_sdcard/system.img".
These backups came really handy to me when I needed to restore system partition after a bootloop or recovery partition after flashing a non working TWRP, but I miss parameter.txt so I want to follow your advice to take a FULL NAND backup to be restored using AndroidTool.
Even after a long search, I couldn't find on the net a copy of my android stock firmware so I need to dump it from my board, something that can be reflashed by AndroidTool. But how can I take this dump ?
many thanks to you too ! I've learnt so much in these few posts !
So you suggested Multiboot as backup tool for android stock and i will surely take a dump with this method.
And thanks also for clarification that steP-nand procedure is just for Armbian so I will use MultiTool (with idbloadr skipping) to flash NAND.