Just started playing with these devices as I've been using openwrt for many years. It's been very hard to find information on exactly what you're talking about here. First, I created my own custom image which I can write to SD Cards. I'd like to write that to eMMC so that no SD Card is needed. Howev...

I have to use a custom Ubuntu OS on these devices and need to use eMMC rather than SD cards. Most of these devices will be remote to me and updating parts of the OS is difficult. It would be easier to send each device an OS update but I'm not sure how that could be done. On OpenWrt for example, it's...