Very cool stuff! Some boards, like the beaglebone, have specialized hw like PRUs or I2C pins. Is it possible to access these with Docker containers? Also, what is the minimum memory footprint? i.e. how many containers can I fit within say 1 GB.
The number of containers is kinda a red herring for a couple reasons. For one, you can make a trivial container and launch as many containers as you like, it really depends on what's in them. For another, embedded devices don't usually need hundreds of containers, they run payloads that are either single-container, or look a lot more like a docker-compose file with a few microservices.
I'm really interested in the answer also!
ARM isn't anywhere near as standardized. There are usually vendor kernel patches, not just for drivers, but dependent on the block layout of that particular ARM board. uBoot is often forked and also specialized. There is no one shoe fits all Grub.