Omarchy OS: How do I make an app launch automatically when I log in?

Add its launch command to your user Hyprland autostart file.

Edit ~/.config/hypr/autostart.lua and add o.launch_on_start("your-command") with the real executable or script name. This starts it with the desktop session and stops it when you log out. Keep the change in your user configuration.

Source: Omarchy manual.