I'd dearly love to do this. I'd even settle for keeping the (presumably ancient) kernel shipped by the manufacturer and just replacing the user space to ditch the hardware manufacturer's pile of hacked together crap and clunky web interface.

All we ever use in practice would be covered by dropbox/opensshd on a minimal rootfs with a shell where we can (presumably) toggle GPIOs through sysfs to power on/off/reset and interact with the serial console over a tty. This is almost certainly what the horrible manufacturer interfaces already build on top of.

But as far as I know, the damn things only accept signed images and aren't easily stripped down and replaced like this?