There are apps, such as iConnectHue, which are able to install a preset on the Hue Bridge that dims the lights or changes the color temperature without needing any computer or phone turned on when the timer fires.

Fixture design is fashion and existing products are not expensive.

The fact that bulbs are 1. small and 2. run on mains electricity is a big complicating factor. By far the easiest way to build this would be with dual-colour LED strips. But that's not how most people want to light their homes.

Electrical engineer here.

What is hard about these?

For a few dollars I can convert 120v to whatever I want.

Sell a different version to Europe

I think it's the cost. You can make a cheap driver off 120V that looks like shit and has terrible thermals.

A solid driver with good filtering and good thermal characteristics is expensive. So you're left with a $15 LED bulb that sits on a shelf next to $5 bulbs, selling to customers who see nothing other than two LED bulbs where one is grossly overpriced for no reason they can comprehend

Sell on their website? They get traffic

As a software developer, the fact that I even have to build custom electrical hardware is a significant barrier.

The fact that this hardware runs at 120v (or 240v in my case) makes it the barrier higher as there's now a chance that making mistakes might kill me.

Additionally, the high power levels mean that adequate cooling is needed, and as a non-expert it's hard for me to know whether I've done that correctly.