I currently have Logitech x530 paired with this USB 7.1 surround sound card:
https://www.amazon.com/LEAGY-External-Sound-Card-8-Channel/dp/B07VSHCGWD
I wanted to connect it to my Samsung smart TV with S/PDIF optical cable, but it didn't work. Optical cable is lighting red, so connection works, but it doesn't want to produce any sound... I've tested the soundcard using USB on my laptop, and it worked flawlessly. TV doesn't recognize USB as an audio outoput, as expected.
As a sanity check, I've tested it with TCL Google TV, but it also doesn't output to S/PDIF output... I even couldn't find a setting for switching to it in audio settings!
To counter that problem, I was thinking if there was any way to avoid using optical with my TV, and just create my own reciever that will connect to TV via bluetooth to stream that surround sound.
I've found project called "balenasound", but I'm not sure if it can stream surround sound dolby audio...
What are my best solutions to fix this issue? Should I continue with Raspberry Pi DIY reciever or I can do something even better?
I think you need to consider my last point more. That device is not a standalone converter. You'll need to run it through a computer.
This is more the type you need. Even then, you'll need to convert the 3.5mm to RCA connections, although many Logitech speakers came with those adapters.