"Selling" the channel button space is part of the business model.
Depending on which roku device you can buy other remotes with different buttons on the internet (second hand or clone). Not sure if oldest "radio" remotes (no buttons at all or gaming buttons) will work on newer roku ( @Tivoburkee would know).
If you want to select your own buttons, and the roku isn't a stick, then oneforall model 7935 is for you, not too expensive and fully configurable!
Not a Roku employee