[boogies]

TinyCore (on the frontpage a while ago) fits an OS with a FLTK/FLWM desktop in 16 MB of storage⁰, but it requires a bare minimum of 46 MB of RAM to boot (regardless of swap space, which it recommends along with 128 MB of RAM).¹

OTOH KnightOS² (not Linux) has a rudimentary (obviously not Xorg) GUI that IIUC runs on TI-73 series graphing calculators with 25 KB of RAM.

⁰http://tinycorelinux.net/welcome.html ¹http://tinycorelinux.net/faq.html#req ²https://knightos.org/

[anthk]

Tiny X existed and Basic Linux ran in those specs:

https://distro.ibiblio.org/baslinux/