Surround sound receiver that works via optical or HDMI. That's what I would recommend over a soundbar that will ultimately end up unusable after a few years. No need to overcomplicate it with HA.
Or... An older Bose soundbar. Bose recently open-sourced some of their older stuff that is no longer supported.
As someone who grew up with older surround sound equipment in the house, I'm just having a hard time imagining a scenario where any network connection at all would need to be involved.