Ok, we’ve tried it ourselves now, looks like both things are necessary - updating the packages and switching to a newer mainline kernel. I’ve created a quick issue on Raspberry Pi’s kernel repository about updating rpi-4.19.y-rt branch with support for Pi 4 8GB. Once it’s done, we can rebuild the kernel and build a new Patchbox OS image, so it works out of the box with Pi 4 8GB.