It would be great to have a pipe, that adds one custom MIDI message to the incoming message.
One use case (which would make a lot of Elektron user very, very happy)
The Octatrack, for example, does not support instant Program Change (like Akai MPC does).
It receives Prg Change message during the pattern being played back and changes it only after the current pattern exceeded.
To avoid that, it is possible to send the Prg. Change command together with the MIDI Note 35, which restarts the Sequencer. This combined message then works exactly like instant Program Change Message.
Right now you need to code on a device like the Axoloti or write a PureData patch that runs on a Raspberry Pi (with Pisound to realize tasks like this.