This ubercorn - Large RGB Pixel Matrix - PIM406 - has 256 big, bright, colourful pixels on a 16x16 matrix that you can control with your Raspberry Pi. Ubercorn is ideal as a big status display, or you can chain several together (up to 8) into a larger square or rectangular matrix.
Ubercorn is like Unicorn HAT HD embiggened! The 256 RGB pixels on its 16x16 matrix can be individually controlled (they're standard RGB LEDs driven by the on-board ARM chip, not addressable pixels like NeoPixels or APA102s), meaning that you can use it for animations and even scrolling text, especially if you chain a couple together.
We've designed Ubercorn with a 2x20 pin female header, just like a regular HAT, so that you can pop a Raspberry Pi right onto the back. You can use the included screws and standoffs to hold your Pi securely to the back of Ubercorn.
If you connect a power supply to the two screw terminals, then it'll back-power your Pi too. With a single Ubercorn and good-quality 2.5A power supply, you can connect the power supply to your Pi and it'll provide sufficient power for Ubercorn also.
Ubercorn can be driven with the Unicorn HAT HD Python library. We've updated the library to accommodate larger-sized matrices, so all you need to do is specify the total width and height of your matrices, the bottom left pixel coordinates for each matrix, and their rotation. If you're just using a single matrix, you don't need to worry about this, and you can just use the software in exactly the same way as Unicorn HAT HD.
Here's an example of how to make a two-wide by one-tall rainbow with two Ubercorns:https://github.com/pimoroni/unicorn-hat-hd/blob/master/examples/rainbow-2x1.py