Yocto doesn't run GUI applications, it's a framework to make your own distro. The fact that many users are too lazy to create a user to run their application as, speaks of the embedded space in general rather than Yocto in particular.

> I'd suggest just looking at another distribution

You won't find one. With many vendors, it's the only option.

It's designed for embedded systems: it's not so much arbitrary GUI applications as a specific one, in fact the OS is more like a library for a single application than a traditional server or desktop OS. It's not that much unlike a single-process docker container, one where it can be quite hard to draw meaningful security boundaries within it. (you can, of course, run stuff as different UIDs, but generally the application needs to have permission to do basically everything on the system, one way or another).

I’ve used it to run autonomous land vehicles. ~60 written binaries and ~20 written libraries, in additional to your bog-standard Linux distro binaries/libraries (core/more utils, ip, user management, etc)

It doesn’t need to be pidgin-holed as a glorified one-app-docker-esque platform. I would argue running a yocto distro as nothing more than a docker host might be the most powerful way to use it even, where the container also runs more than a single “thing” if you will. Just abstracts away the hardware layer from the software layer so as not to muck with the bsp.

> Running arbitrary GUI applications as root is such a huge red flag

Yes, but...

For many embedded applications, getting any sort of execution on the GUI thread/process is game over anyways.

idk what this says about anything