How can I make Home Assistant see what it believes to be a RGB controller as a one-channel dimmer?

I have a bunch of Gledopto “5-in-1 Smart LED Controller” (both regular and Pro versions). I have configured them as “dimmer”, which is a single-channel mode (all outputs responds only to brightness commands).

One time out of 30 or so repeated tries to connect them to Home Assistant has been 100% succesful (i.e. it shows as a dimmer), all other tries it has shown up as a RGB or CCT controller, which means that I get a color picker or color temperature slider in the UI. Light control using brightness works fine, but I want to get rid of the non-working color picker/slider on my cards.

Looking at other questions, there are a lot of comments on how to change the device type from “light” to “switch”, using device_config in configuration.yaml, but nothing about changing the configuration of a light device from RGB/CCT to single-channel dimmer - they are both light devices. How do I go about doing that?