It depends what we're talking about. Specifically with ARM processors, it isn't trivial to add drivers separate from your OS deployment. Microsoft DOES work with (and update) third party hardware directly for Windows 10 Mobile devices. And this is true for their third party phones from HP, Acer, etc. as well.
(Note, I have a Windows Mobile device from 2014, and I still receive the latest security fix on Patch Tuesday around 1 PM, every month.)