These interfaces can be cute to play with, but there's a reason that fbdev is deprecated on Linux - it's not a good interface outside toy examples. wscons may be more powerful, but I don't think it can be used to fully enable modern accelerated display devices, although do correct me if I'm wrong.
Despite some confusion in terminology, modern interfaces also operate on frame buffers, but with an API for switching them out atomically. Likewise, your display server (at least modern ones) just take your client window as a completed frame buffer, and mainly serve to let multiple applications all show their frame buffers without having to worry about what other applications are doing. Frame buffers all the way down, just with support for DMA, atomicity, fancy formats and color spaces, etc.
You can use the appropriate modern APIs to make a single, exclusive graphical application with all the benefits of modern display hardware easily enough. That is, after all, what your display server is. You just don't gain much - just a little bit of saved sideband IPC.
X11 makes it seem like a display server is a complicated thing that has to support drawing and what not, but with alternatives like Wayland, a full screen client buffer is handed off zero-copy from the client application tot he hardware without being looked at.
I remember Links, the text-based browser that runs in your terminal, had a framebuffer mode that you could use to get rudimentary graphical web browsing on a system with no X11 installed.
On a parallel note, this brought memories of SVGALib.
Very nice, I am very interested in raw framebuffer graphics and applications.
> wscons may be more powerful, but I don't think it can be used to fully enable modern accelerated display devices, although do correct me if I'm wrong.
As I mentioned in the text, I think that's the difference between WSDISPLAYIO_MODE_MAPPED and WSDISPLAYIO_MODE_DUMBFB. The former allows access to the hardware registers whereas the latter does not. Obviously, if you choose to use the former, then you are tied to a specific graphics driver. (But I'm not sure of this.)
And yes, agree, what I described is not great for performant results, but there is a lot you gain from the simplicity of this approach if all you want is toy around. I feel we lost a lot of this simplicity over the years, but it's "still there" if you don't care about optimal performance.