I have been digging around in this space searching for a good solution where I might have connectivity, but I also might not. So I need to be able to update off a USB as well. Mender seems to have a story for this. Resin.io told me to have people hook a hotspot up. Our units can be in the middle of factories in the middle of nowhere. Its not always possible to be connected.

Tried resin.io and while it had good ideas, it was difficult to integrate. It is also completely dependent on their hosted management system. Which can be good, but is another hurdle to get past. Mostly because we would have started at greater than 25 devices and would have rapidly hit 200. So its hard to get our owner behind that up front.

Mender has been much easier to get going. Its dependencies are far less and without the docker containers easier to get going initially. Docker I think will have its day, but host<->container configuration for peripherals is kind of clunky.

Also Mender can be self hosted so that makes it far less friction for me to get going with.