I wonder what the dev/CI process looks like on this.

Will it ultimately be manually loading a build into specific hardware each time, or is there a level of automation that can be done here?

m1n1 does a lot of fun stuff here: https://asahilinux.org/docs/sw/tethered-boot/

It allows you to do some remote control and automation for kernel loading and debugging where you get a very thin layer in between the real hardware and the kernel, without affecting the hardware I/O behaviour.