I’ve never had a sound bar but I was under the impression that they were typically marketed to people who wanted to replace nasty TV audio without going to a full sound system. I’m curious as to why you added a streambar? It seems like a conventional/cheaper Roku player would send audio to the TV which would then go out to the receiver and speakers.
As for the idea of bidirectional optical, in the audio/visual world (unlike for example ethernet) connections tend to be inputs or outputs. Googling around a bit, all the optical ports I see are labeled in and out.
As for how many people do this? Well, I did back in the 80s and 90s, but in the 2000s I’ve been using an AVR and now life is very simple:
All input devices ----> (HDMI cables) ----> AVR ----> TV and speakers.
Just something you might consider in the future.