free software implementation of sony playstation bios (usable with duckstation emulator, the README also says it will work with real consoles):

github.com/grumpycoders/pcsx-r

note it won't work with older emulators like PCSX-based ones (except PCSX-Redux), very likely because PCSX did not emulate the 'load delay slot' feature of mips cpu properly or other improper implementations.