Yes, for a while I used the optical from my TV to feed my 2 channel system for TV sound. You don’t get hifi. you basicly get dual mono and it creates a single center image. but it was quicker than switching fo full dolby mode and good enough for TV that was only available in mono anyway. I used my HT system for things that were provided with multichannel sound.
My TV is an LG. I had to select "optical out" as my sound choice.
I’ve abandoned my ROKU. I find my TV is a better streamer than the roku and I use ARC to send the sound to the HT reciever. I feed my 2 channel system with pre out for those 2 channels (you have to have a spare input location on your amp). ARC makes it easy to switch to this since the TV prioritizes ARC when it is enabled.
Jerry