Hi there,
as it's a HIGHLY cumbersome process to flash the internal storage, I made a glitch and erased the GPT.
After some bouncing between rtfm and madness, I have finally flashed Ubuntu desktop and it works, but!!! I have no idea how does it mount the partitions, as the GPT is empty for the moment.
Well, I could leave it as is, but feel somewhat uncomfy for a case when anything goes wrong again: I'm planning a LOT of experiments with this SOM.

Would anyone please post a correct GPT for the SOM and ubuntu18? Or is it common between all these OSes (except armbian, yes, I know).

Thank you.