ROKU people, please respond. Your web site does not list one remote as compatible with the sound bar.. You are resolving this with your online resources, and you’ve made it impossible to email customer support. Come on!
All roku TV's, recent sticks, and consoles all can be paired to same wifi-direct remotes, I don't have sound bar but I would assume it can also. List sound bar model number from in the battery compartment. It looks like a rc-al7 remote which sold separately and will with roku stick+, premiere+, recent express+, and roku Ultra. Can the headphone jack on ultra remote work with the sound bar, that can not answer.
I can tell you for sure if a remote doesn't have particular roku model number listed on the roku accessory page the mods are not going to answer it, in fact even if and end user like me can attest that it works, they may wipe my above answer from view.