unipixel is a package designed to be used interchangeably with the adafruit-circuitpython-neopixel package for the purposes of testing and development on systems where, for whatever reason, actual neopixels aren't available.
unipixel works by wrapping the █ (0x2588) unicode character in ANSI color escape sequences. This method requires a terminal that supports both unicode and true color for unipixel to render properly.
A list of terminals that support true color can be found here.