Vertical dock on elementaryOS 8

I prefer my dock on the left side of the screen and the new elementaryOS 8 Wayland compatible dock's design is to explicitly not support that. This is because the dock is visible in the workspace switcher and allows the user to drag windows to other workspaces using the dock.

If you're happy to lose that functionality and are using the Classic login session then you can reinstate Plank as follows:

Disable the Elementary Dock (Correct Way)

Create a user override:

cp /etc/xdg/io.elementary.desktop.wm.shell ~/.config/

Edit the file:

nano ~/.config/io.elementary.desktop.wm.shell

Remove or comment out the dock block:

[io.elementary.dock]
launch-on-x=true
args=io.elementary.dock

Log out and log back in.

Result: the elementary dock is never started and does not respawn.

Start Plank

Use standard XDG autostart. File: ~/.config/autostart/plank.desktop

[Desktop Entry]
Type=Application
Name=Plank
Exec=plank
OnlyShowIn=Pantheon;
X-GNOME-Autostart-enabled=true

(Optional) Add a small delay if you ever see geometry issues:

Exec=sh -c "sleep 2 && plank"

Verification

pgrep -a io.elementary.dock # should produce no output
pgrep -a plank # should be running