The company Giiker came up with the first ever Bluetooth cube sometimes in 2018. Currently there are 5 versions you can buy on eBay, Aliexpress etc. and some selected stores around the world. All versions are supported by CubeSmith, but I recommend buying the latest versions (i3S and i3SE). One cube is enough for most of the effects, however, the real killer is the cube cloning effect, for which you will need 2 of the bluetooth cubes.
Xiaomi also came out with a bluetooth cube, called the "Xiaomi Mijia Magic Cube". Currently this model is my favourite of all available bluetooth cubes, see details below.
Also there are bluetooth cubes from GAN, and now CubeSmith supports all of them.
Xiaomi Mijia Magic Cube
As I mentioned above, currently this is my favourite bluetooth cube. This bluetooth cube has a replacable button battery (1632) therefore it has no charging holes. The body of the cube is black matte plastic, and the stickers have nice pale colors. You can re-sticker it if you want a more authentic look. The cube goes to standby after 15 minutes if not connected, but stays connected forever once you use it. I recommend buying it on Banggood or Aliexpress, it only costs around $18 - $25 these days. I recommend ordering 2 cubes at once. :-)
The more expensive GAN 356i has a gyroscope, so we can tell which side is facing up. The cheaper GAN 356i Play lacks the motion sensor, but it's battery life is significantly better. Both models come in stickered and stickerless versions. The cube itself is really light, and it doesn't beep when charging or connecting/disconnecting. You should buy these cubes directly from GAN:
This cube is the latest addition to the list of compatible cubes. Announced in September 2020, this cube is a special one. It has a rechargable battery, doesn't make weird noises when turned, doesn't beep when connecting or disconnecting. Always ready, no need to wake it up. It only needs restickering, as the white center has the Rubik's logo, and the yellow center has the charging holes. After restickered, the cube can be charged after temporarily removing the plastic cover of the yellow center. The price of the cube is quite high, but I think it's worth buying.