Try looking up Pilot or PIAA for a replacement, but these are a sealed
unit like your headlights, and will require replacing the entire assembly.

PIAA may make an exact replacement, but...$$$$$

We still have the factory original fog lights in our Sequoia.  For a while,
fog lights were yellow, but automakers have gone away from yellow and
started mounting them as low in the vehicle as possible.  This is because
the advantage of fog lights does not come from the color of the light, but
rather from the vertical separation between the driver's eyes and the fog
lights so that the glare does not come back at the driver.  The thinking
behind yellow lights was that they would cut glare.  In tall vehicles like
the Sequoia, there is quite a bit of vertical distance between the fog
lights and the driver, and glare from the fog lights is not really an
issue - there is more glare from the headlights than from the fog lights.
I've only used the fog lights on a few occasions where visibility is so poor
that vehicle speed is way down anyway.

I have never noticed yellow fog lights on another Sequoia, but a google
search of "toyota sequoia accessories" came up with lots of hits.
Autoanything.com had several different fog light styles, including PIAA 510
Series that they claim fits in the factory opening.