I got Linux running in a PDF file using a RISC-V emulator.

PDFs support Javascript, so Emscripten is used to compile the TinyEMU emulator to asm.js, which runs in the PDF. It boots in about 30 seconds and emulates a riscv32 buildroot system.

linux.doompdf.dev/linux.pdf
github.com/ading2210/li...

I made a Doom source port that runs within a PDF file.

PDFs support Javascript, so Emscripten is used to compile Doom to asm.js, which is then run within the PDF engine. Input/output is done by manipulating text input fields.

doompdf.pages.dev/doom.pdf

github.com/ading2210/do...