All you are writing to the LEDs there is a 0... the character 0 actually, so decimal 48.
Did you try writing something else to it?
To vastly oversimplify, the LDP8806 protocol works like this.
3 bytes per pixel (not usually in RGB order... depends on the manufacturer) where only the first 7 bits are used, so 21-bit color total.
The 8th bit (or bit 7 in 0 indexing) is the "latch" bit. This bit MUST be 0 when sending color data. Then, when you are done, send a byte with bit 7 set to 1. I always just send 0xFF since any byte with bit 7 set is ONLY used as a latch, meaning it then tells all the ICs to set the LED color to the new data.
So, I would try sending this array of bytes to your strip via pigpio:
[0x7F, 0x7F, 0x7F, 0xFF]
That should light the first pixel white.
And yes, you could absolutely utilize pigpio with a new driver or appending to the original.
First, take a look at this: https://github.com/ManiacalLabs/BiblioPixel/blob/master/bibliopixel/drivers/spi_driver_base.py
That is the base SPI driver. Ideally, we could modify that to optionally use pigpio.
But also check out this: https://github.com/ManiacalLabs/BiblioPixel/blob/master/bibliopixel/drivers/LPD8806.py
For the LPD8806 specifics.
I honestly think the easiest would be to modify spi_driver_base and add a new parameter to the init called use_pigpio and another pigpio_interface which would be the SPI ID (0 & 1 are the original and 2 is the aux SPI port you are trying to use). Then, if use_pigpio is set to True, use the pigpio sub-system instead.
I'm certainly happy to help out making these changes. I have all I need to test it, but always good to have more than just me testing things. And I'm releasing a new version soon anyways
Definitely try just sending those 4 bytes to a strip before making BiblioPixel modifications... no point in trying if pigpio doesn't work in the first place.