Roku Express 4K+ has no sleep timer
zenzland, no Roku devices that aren't actual TVs have a sleep timer. There's a place for features to be
ignored... uh... I mean suggested. 🙂Suggest a Feature | Roku Community | Roku
A couple of notes: if the Roku device had a sleep timer, it still wouldn't ever turn off as they never do. At most it would stop streaming and that's pretty much what the Bandwidth Saver is for, although it's fixed at four hours. I think some would like more control over the timeout period. It couldn't turn off all TVs since not all TVs support a mechanism for a connected device to turn it off (like CEC), but I'm guessing most new TVs do. Likewise, setting a sleep timer on a TV doesn't stop the connected Roku device from streaming.
There's a thread asking for feature suggestions for the remote, so you might want to post the sleep timer idea there - a sleep timer button for Roku players. Any discussion about a sleep timer in that thread as of me writing this is about the sleep timer button on Roku TV remotes and will/has confuse(d) people without a Roku TV.