So I did some additional testing of the - as far as I can tell - very competitive X900C speedlite.

First some impressions of the actual (fixed) brightness of the LED videolight (actually 2 high power LEDs). I compared it to a Aputure AL-198C. This is a bi-color LED panel ... not the best or brightest on the market, but it should give a good impression. The camera was set to manual and white balance also fixed (I think it was set to flash-WB). You can clearly see, that the Pixel-LED is much cooler than the Aputure ... even the Aputure was dialed down all the way to the coolest color temperature. The beam of the Pixel-LEDs are also much wider spreading than the Aputure ... thats why I placed the speedlight in front of the LED panel to compensate for the difference.
The Pixel-LEDs are a little bit brighter than the lowest power setting of the Aputure. This should be useable for videowork, not so much for lighting a whole person.

Now just a brief test whether its possible to light a portrait very close with the constant LED light of the Pixel.
Camera settings: F2.8 - ISO400 - 1/80s
It can be done. ;-)
But you could also use it this way as a modeling light and then use flash for the shot. Or to help focusing the camera.

Now finally for some on-camera TTL testing. Camera set on manual and flash exposure compensation for 0 / +1 / +2 / +3 and 0 / -1 / -2 / -3.

Looks good, no complaints here. Should there be, you ask? There were older speedlites from Pixel that seemed to struggle with constant TTL exposure, so its not an uncommon issue.

Bouncing around with the flash in TTL? Sure, set the camera on manual and TTL no exp. compensation.
From left to right: bounced over the right wall / bounced over the left wall / bounced over the ceiling

Camera turned sideways (portrait orientation) set to manual mode and TTL on the flash.
to the left / to the right

TTL frontal flash with auto zoom (70mm, because the lens was set to 70mm too) and manually set on 20mm (widest setting).

Now I want to check how the flash behaves when set to 1/2 power and triggering it in short successions.

Well you can see that the power slowly declines, so the speedlight doesn't wait long enough before it can be triggered again. For event photography or portrait work this is isn't so good - when the power output isn'
t consistent in case the Pixel is triggered fast.

Ok, but what if we wait just a little bit longer.

Now, this at least looks consistent. :-)

Last lets see how the minimum power setting of the flash (1/128) is compared to the LED. Camera is set to manual 1/50 - F2.8 - ISO200

So 1/128 is still very powerfull when the LED light is barely visible at 1/50s. In other words, the LED light won't bother the flash exposure and can be switched on for modeling light purposes.