I want to auto-start mate-panel when starting sway.
Your autostart applications such as cloud sync daemons and other utilities are added to the Sway configuration like this:
exec nextcloud
… where “nextcloud” is an example of a application to start after login.
exec swaymsg "workspace 1; exec kitty;"
exec swaymsg "workspace 1; exec google-chrome;"
exec swaymsg "workspace 2; exec thunderbird;"
exec swaymsg "workspace 3; exec hexchat;"
exec swaymsg "workspace 3; exec teams;"
exec_always xterm& xterm&
gives me two xterm windows when I load/reload my i3 config because the exec line is passed to the shell, where '&' will launch the programs in the background. Maybe Sway allows you to do something similar?