In tmuxinator you may add synchronize: after to a window element to let it set synchronize-panes: on after the panes' commands have been executed.
In tmuxp I can enable pane synchronization by setting

     options:
      synchronize-panes: on

However, this enables synchronization before the panes' commands have been executed. So I cannot execute different commands in each synchronized pane.
It would be great to have a options_after: configuration element to make such constructions possible.