Here’s a perfect example of the Renard player that you’ve mentioned a few times. Just an external PIC micro that plugs into the beginning of a Renard serial chain and just sends commands without a computer.
There was talk about one that used a plug-in to program external memory. There was also a discussion about one that listened to the standard Renard plug-in and recorded the values and timing of a sequence from a PC. The discussions seem to end when someone suggests playing an actual sequence file and emulating Vixen.