Just got my Steam Deck and have lots of questions, but most of what's out there seems to be aimed at non-technical (Windows) users (but ours is a pure Linux—Debian/Ubuntu/Mint—household ...

For example:

• What's the sanest way to get an ssh key on the thing and enable sshd?
• How do people cope with the read-only root fs?
  I know I could just disable it and just live with having my changes periodically overwritten, or even just wipe it and put 22.04 on; Flatpak may be ok for GUI apps on such a device, but for stuff like emacs, rsync, a full complement of gstreamer plugins for vanilla/TKG WINE, ... nah.
  So assuming I want to keep SteamOS and get with the "immutable root" idea for now, what is the Arch way? Some kind of overlay fs, a chroot / lightweight container / ...?
• Anything I need to know about KDE, coming from Gnome? Haven't touched KDE since the early 2000s ...
• Is there a FAQ, tips & tricks collection, HOWTOs, ... aimed at Linux users?

• Enabling ssh does not require sudo / root privileges or switching the root fs to rw. Running systemctl enable --now sshd in console as the regular user (deck) will do it. /etc is on an overlayfs and apparently the user's privileges are sufficient.
  You do not even need to set a password for the user, as long as you're willing use an ssh key and transfer that via other means.