One of the main reasons I am considering Channels to replace Plex is some of the server side customization that is possible for the endpoints. What I am really trying to do is make it as basic as possible to watch tv. I'm wondering if there is a way in Kiosk mode for only the TV Guide to show up as an option?
Yes. Using Server Side Settings you can disable all navigation/sidebar options except for the guide. The options you want are under General > Manage Navigation and Server Side Only > Kiosk Mode.
In that situation though, the sidebar will still be present, but only contain the "Guide" and "About" entries.