Interesting comment, because according to https://en.wikipedia.org/wiki/PDP-7 the PDP7 (the first computer "UNIX" ran on) had ~9.2KB of memory (supporting up to 144KB).
Most contemporary SoCs will have more memory (and compute power) than that.
And frustratingly all "lacks MMU" and V6 UNIX binaries don't just run. Imagine the world where random IoT gadgets all run backported GPLv2 GNU/Unix systems and crashing left and right.
Instead there's a massive gap between Linux-capable systems and RTOS-focused systems despite, like you said, the latter now being bigger and better than real shared UNIX systems.
