Generic USB Wifi Switch
General Notes
There are various models of these generic USB Wifi switches. They come with 1, 2, or 3 individually switchable USB output ports, but only the first passes data.
GPIO Pinout
| Pin | Function | 
|---|---|
| P6 | LED | 
| P7 | Relay 1 | 
| P8 | Button | 
| P26 | Relay 2 | 
| P24 | Relay 3 | 
Flashing
They use a Tuya CBU module with easily accessible flashing pins.

The 3 output model restricts access to the uart2 pins for logging, but they aren't necessary for flashing.

I used ltchiptool to backup the original firmware and flash an esphome uf2 binary to it.
Configuration
bk72xx:
  board: cbu
switch:
  - platform: gpio
    id: relay1
    name: "Relay 1"
    pin: 7
  - platform: gpio
    id: relay2
    name: "Relay 2"
    pin: 26
  - platform: gpio
    id: relay3
    name: "Relay 3"
    pin: 24
output:
  - platform: libretiny_pwm
    id: led
    pin: 6
light:
  - platform: monochromatic
    name: LED
    output: led
binary_sensor:
  - platform: gpio
    id: button
    pin:
      number: 8
      inverted: true
      mode: input_pullup
    name: Side button
    on_click:
      then:
        - switch.toggle: relay1