Starting a spidev program during U-boot or right after U-boot

So I need some guidance on how to make spidev run at the very beginning of the kernel init. I am using an ILI9341 display connected to the pocketbeagle that is being driven using SPI. Thing is, I need to “send” an image to the display during boot. For that, I need to start spidev at the very beginning of the boot process, and I am not really sure what process starts spidev. I am not sure if it’s something started by a systemd process or elsewhere.

“Important” things like GPIOs and I2C appear to be running at the very beginning of the boot process. How could I do the same thing with spidev?

I am a little unclear where in the boot process is the pocketbeagle’s device tree being “declared”? Where in the boot process does /dev/spidev becomes available? And how can I make it start earlier?