What are the rules in 1d ?

It only starts out 1-dimensionally, it continues to evolve on a standard GoL grid.

Then, importantly, it collapses itself back down to a 1-dimensional copy of its starting representation, but translated.

Specifically, after 133_076_755_768 steps, the 1-dimensional pattern reoccurs translated by two pixels. On skimming the thread I haven't determined if that shift is parallel or perpendicular to the line.

I think it has to be parallel by symmetry.

Can it leave other bits behind after it moves?

By definition of a pure spaceship / glider, no it can't. If it emits persistent "exhaust" that's a "smoking ship"[0].

[0] https://conwaylife.com/wiki/Types_of_spaceships#Smoking_ship

IIUC, "smoke" is ephemeral by definition. A spaceship/glider that leaves persistent "debris" in its wake is called a "puffer":

https://conwaylife.com/wiki/puffer

Smoke refers to fairly long lived debris that eventually dies out, the term for one that leaves permanent debris is a puffer.

No, if it does it's called a puffer.

The pinephone hardware feels like a prototype due to the old A20 cpu (heat problems, poor battery life).

The lesser-known SHIFT6mq has an actual mobile chip and apparently works correctly as a phone under postmarketOS (only GPS, NFC and Camera missing): https://wiki.postmarketos.org/wiki/SHIFT_SHIFT6mq_(shift-axo.... There are pointers on the wiki to hack on the camera if you want to help the cause.

The Fairphone 5 is another good candidate for hacking: calls and camera are not working: https://wiki.postmarketos.org/wiki/Fairphone_5_(fairphone-fp...

I found this lesser-known case: Sagittarius 8-bay https://www.reddit.com/r/DataHoarder/comments/1d0z2l3/sagitt... 8 bay while remaining compact with good airflow around disks.