The easiest analogy i can make of an Internet of Things device giving you root access or not is like looking at the Telstra TV options. It is a rebadged Roku device. The official Roku app selections are quite broad. Telstra however gimp it so bad only a handful of apps are options. Lots versus limited here. Sure you can sideload ONE custom app via the dev mode on the Telstra TV - a while back i made a roku app from scratch to suit my needs deployed like this, but that's it and confined options at that. Tough titties if you want something specific!

All my SBCs give me root access.. and i am only limited by arch or vendor/dev support for diverse apps.. which is generally good anyways. Virtually anything can be set up one way or the other, and there will be a HOWTO.