I'd love for this to be the case. I have a handful of raspberry pi projects that I just want to boot and run a single executable. I don't need or want the rest of the OS included with the likes of raspbian etc. I'm currently working on a dietpi customization but this would be even better if it worked.
There's also Buildroot which has a bit of a learning curve (it's still easier than Yocto/Angstrom IMO) but is capable of producing highly customized, tiny embedded Linux images. At this time, there are board configs for pretty much every Rasperry Pi variant out there.
The functional equivalent of a Debian base install, including kernel, bootloader, and systemd init (approx. 350 MiB) is about 20 MiB (compressed) when built with Buildroot.