I am building the os as well (based on yocto). Want to use swupdate and a dual partitioning system but I am stuck with uboot that don't want to boot and attaching a serial connector is not that easy/safe because the Neuron is already installed. Options I have are either to buy another unit or to patch swupdate to use the default raspberry pi bootloader (even if the fallback policy in case of a broken update is not that easy to tackle with the default bootloader).
Currently I am mainly working on network security because I want to have a mutual tls between the remote relay server and clients but updates are the next topic.
Will keep you updated.