I already hate this Win10 idea... but to each his own I guess. That being said, it looks like Microsoft developed some 'core' code for several devices so they can be accessed from a Windows 10 computer. I haven't gone further into their documentation. If the MS 'core' takes over the whole device, then it's an actual kernel, and that is very limiting IMO. I'm definitely not interested by that! However, if the MS 'core' can be one of the OpenWrt processes, then that can actually be useful.
Microsoft being Microsoft, and vulnerabilities found in their code on a much too regular basis, do we really need our garage door hacked by thieves, or a ransomware criminal asking for bitcoins to give us back the control to the house thermostat? And what about the coffeemaker?