These kinds of articles are always fun: essentially playing golf with the size of an executable or some other file format.

To plug my own entry in the genre, back in 2006 a few members of the Nintendo DS emulation scene tried to put together the smallest DS ROM that would still do something visible on the system: https://imrannazar.com/hacks/the-smallest-nds-rom

We ended up with a 352-byte file with two minimal executables, for the ARM7 and ARM9 cores. I've yet to see a .nds file smaller than that.