OK, I finally spent an hour or so and went to Logitech's page with wireless keyboards at http://www.logitech.com/en-us/keyboards ... ice-combos
By a Wikipedia page at https://en.wikipedia.org/wiki/Bluetooth_low_energy
Bluetooth Smart Ready indicates a dual-mode device compatible with both
Classic and low energy peripherals.
Bluetooth Smart indicates a low energy-only device which requires either
a Smart Ready or another Smart device in order to function.
So "smart ready" is the best to have.
There are several Logitech Bluetooth keyboards, only the k830 also has a touchpad. I didn't consider anything that wasn't fullsize. Logitech also pushes something they call "unifying" https://en.wikipedia.org/wiki/Logitech_ ... g_receiver
The k830 can do that, a cheaper keyboard with touchpad, the k400, does only that. There's some support for unifying in the Linux world. It may well be a protocol for keyboards/mice over WiFi, Logitech's adapter looks like a standard USB WiFi dongle.
The k830 is marketed as a "living room" keyboard and also has backlit keys and a built-in rechargeable lithium-ion battery. Charging is over USB. List price is $99.99, street price by Froogle is about $45. http://www.logitech.com/en-us/product/l ... 30?crid=27
It only does BLE/Smart. In the manual at https://www.logitech.com/assets/50714/i ... -guide.pdf
there's no real mention of Bluetooth but it does say you can use the keyboard to control some TVs. I'd make sure there was a good return policy I guess.
I also found this one on Aliexpress for ~$50 which has the unique feature of the touchpad doubling as a numeric keypad: https://www.aliexpress.com/item/Keyboar ... .27.OTZtyB
Only Bluetooth 3, not backlit.