Shelly rgbw2 custom transition effect

I have a shelly rgbw2 led controller connected to an led strip and configured for mqtt integration with home assistant. The shelly has the default firmware that comes with it. It works for commanding discrete colors and brightness. Now I would like to create a transition over 10 seconds or so between 1 color and another. Is there any recommend way to do this? There are a couple pre-defined effects but they don’t do what I want. I appreciate any ideas.

i just searched the forum for the same thing - only difference is, i flashed the rgbw2 with tasmota