There are interactive message buttons, but they dont flow neatly in the text. It should be possible to write a longer post, and reference commands and parameters in the text.
Once the post is posted, they become clickable by everyone which would in some way ask for confirmation or just pre-fill the text-input-area and allow the users to execute said command.

That way one could not even better educate users of (custom) commands, but could also help them prefill the arguments of commands.

Example: I could write:

hello there, it seems, like you want to use /command asdf for asdf and /command asdf qwer for something else, we also offer /another-command --all to do all other cool things.

If the users click on /command asdf it will ask them, if they want to execute said command with the given parameter. Or it would just pre-fill the text-input area so users can customise the command and arguments, before executing.