It looks like even if we bought a Roku subwoofer or wireless speakers that we wouldn't be able to use them in the UK because the software on the Roku Streambar currently only allows it to be connected to the remote.
Roku on Twitter never reply when I ask about the sub and surrounds. When I had an issue with YouTube they answered writhing 10mins. It seems we are left out all the time in the UK. If they brought out these products in the UK sales would be really good. Not everyone wants to be tied to a giant like Apple, Amazon for streaming and speakers. The fire tv can be connected to two echo studios for a real punch of ATMOS. So why can’t we get some decent kit here ROKU? We don’t even get the ROKU ultra or the bigger soundbar.
If you want a streamer with sub woofer etc in the UK then it looks lke your best option is a fire TV device, a quick search shows plenty of soundbars with sub woofers etc equipeed with fire TV on board .