This is what I used for the red door: https://amzn.to/43dp9e9 “USB Lights Bars 12 Inch, 3 bars chained”.

I’m powering this with a custom-made USB A-to-C adapter, which is turned off and on by a contact switch on the door. That works well, but it’s been bugging me because the light is stuck in the white-ish 9000K mode instead of the better looking 3500K 6500K mode. So I took one apart to see how it is built inside.

It contains a USB C with a 6-pin connector. That’s a “power-only” connector: GND / VBus / CC1 / CC2 / VBus / GND.

So essentially they “abuse” the CC1/CC2 lines as ground for the yellow-ish LEDs.

When using a USB A-to-C adapter, only the GND and VBus are connected. The CC1/CC2 lines are not, and I cannot turn on the yellow LEDs. Now, if I were to bridge the 2 bottom resistors, I’d connect the CC1/CC2 lines to VBus and have all the LEDs turn on -- and by cascading effect so would any other bar connected to that one.

Subtlety stepped outside for a moment.

I think it’s safe to say that we probably do not want to connect this to any “smart” USB C power supply. In this case, it’s likely that nothing will happen as it won’t be able to negotiate power on CC1/CC2.

Note that the list for the light specifies the colors as:

• 9000K … I can guess that’s a good description of the white LEDs.
• 3500K … That would be the yellow-ish LEDs.
• 6500K for the combination. It does feel like a “cool white” indeed.

Ideally I’d love a “warm white”, which would be the yellow LEDs only. Given how the light strip is wired, that would require powering them only from the CC1/CC2 pins and not from the VBus pins. I’d have to check how I created my custom USB A-to-C adapter, and if I rebuilt it, now I probably rewire it to achieve that 3500K effect only.