In search for a software recommendation:
The remote session management app "mRemoteNG" for MS Windows comes with
a functionality by which a command can be entered to its "Multi SSH"
input field, and this command is then sent to all SSH connected remote
systems at once as if the command would have been typed in at each
single of the SSH connected remote systems CLI individually.
Do you know about such feature to be implemented in some Linux tool?
Maybe it even exists as a plugin for tmux?
Best wishes, Marco.