Move them to a cheap Onn Android TV device. You can configure it with a completely clean interface with no ads at all, and no asshole company's changing the menus constantly once you install an alternate launcher. You can also debloat it like any other Android device and shut off most of the tracking (as much as is possible with Google involved anyway).
I bought my first one yesterday. After configuring it and seeing what a massive improvement it is over Roku I bought a couple more today. 2K ones are on sale for $15 right now.
