You can purchase the roku voice remote from walmart or best buy. It won't work out of the box it has to be paired to roku tv.
Also at Walmart they have One-For-All urc-7935 streamer universal that works great on roku tv's. Have three on my Tcl, Insignia, and Hisense Roku tv's.
If you have UEI made cable remote, if it takes 5 digit codes its made by UEI, I can probably give you the commands to work the roku tv. Name the brand and model of remote?
Roku Community Streaming Expert
Help others find this answer and click "Accept as Solution."
If you appreciate my answer, maybe give me a Kudo.
I am not a Roku employee.