SteamOS (the operating system for the Steam Deck) is based on Arch Linux (the blue A), so that’s what’s going on in the bottom panel.
The red swirl is for another Linux operating system, called Debian. I don’t know what OP is referring to by Steam ‘leaving’ Debian in the top panel.
Any ship traveling towards another ship would have its nose pointed towards it.
If both ships travel towards each other, their noses would be aligned, but their roll would likely be different.
That’s a bit different from what’s being shown in the comic where ships seem to have any orientation, no matter the context.
As for a galactic up/down, the galactic disc would be the obvious reference. That still leaves a 50/50 chance that two civilizations would choose the same direction as up.