I’ve got a Shelly RGBW2 (RGBW) which handles 4x alog PWM on the ‘next projects’ pile, and intend to use either Tasmota or WLED as it’s just an ESP8266. There are other COTS controllers out there, such as one from Quindor.
https://www.shelly.cloud/en-us/products/product-overview/shelly-rgbw2
https://tasmota.github.io/docs/devices/Shelly-RGBW2/
I have written my own client devices using Python + MQTT, and the only advice I can offer is that MQTT discovery is instant - e.g. if you experiment with mosquitto_pub, HASS will react instantly with changes to the advertised device so you can try different ways of defining your device in real time.
There were some issues with Zigbee RGBWW bulbs, but when better support for different device definitions came in last year (e.g. mapping between colour spaces) the definitions changed and my Lidi Livarno cheap bulb works with both a COLOR wheel and TEMPERATURE slider. Again, might be worth a read for inspiration.