How do I change smart bulb brightness with a smart dimmer switch? (Detached Dimmer)

Configuration
#1

I have a Ceiling Light Fixture with 3x RGBWW(color temp control) (costco feit) tuya bulbs
I have replaced the switch wired to this fixture with a Shelly Plus Wall Dimmer

the Shelly Plus Wall Dimmer does not have a detached switch mode so I plan to cap the load output with a wire nut and wire the load cable from the fixture into the line wire nut.
(bypassing the switch so the smart bulbs have continuous power)

I created an automation with the trigger shelly switch on which sets the bulbs on and a second automation for shelly switch off turns the bulbs off

How do I make an automation for the shelly dimmer brightness to change the bulb brightness?

is there a different smart switch I need to buy to use as a “detached dimmer” to control smart bulb brightness?

#2

If you are ok on keeping tuya you could use either a feit dimmer setting the “hardware” minimum brightness to 100% by

  1. pressing and hold both up and down at the same time till the dimmer button light starts to blink.
  2. Press the up button till the max
  3. press both up and down at the same time again till the blinking stops.

The you can have an automation to sync them like this:
I probably should make this a blueprint instead.

But be mindful that using other dimmers it can be an issue if they support hold dimming as the smart bulb devices can’t handle been bombarded with so many very rapid commands. So I recommend adding a small delay of 250ms before running the call service command.

alias: Kitchen Recessed Sync Automation
description: ""
trigger:
  - platform: state
    entity_id:
      - light.kitchen_recessed_lights_local_tuya
    attribute: brightness
    for:
      hours: 0
      minutes: 0
      seconds: 0
    id: Recessed_Brightness_Changed
condition: []
action:
  - choose:
      - conditions:
          - condition: trigger
            id:
              - Recessed_Brightness_Changed
        sequence:
          - if:
              - condition: state
                entity_id: light.kitchen_down_lights_group
                state: "on"
                for:
                  hours: 0
                  minutes: 0
                  seconds: 0
                enabled: true
            then:
             # Introduce delay of 250ms if needs to lower the the throughput to the smart bulbs
              - service: light.turn_on
                data:
                  brightness: |
                    {{
    state_attr('light.kitchen_recessed_lights_local_tuya', 'brightness')
                    }}
                target:
                  entity_id:
                    - light.kitchen_down_lights_group
                enabled: true
mode: restart