All (?) PlayStation games use flavours of the GCC compiler; typically the PSYQ toolchain from SN Systems.
The existing tools designed to support N64 decompilation, such as m2c, asm-differ, and decomp-permuter, are built to work with ELF object files. Since the PSYQ toolchain generates proprietary object files, tools have been created to convert these into standard ELF objects. Alternatively, projects like maspsx can be used to produce output identical to PSYQ compilers and assemblers, but natively in ELF format.
A fully-fledged executable analysis tool. It is open source.
You may want to use the ghidra_psx_ldr plugin, which automatically creates the right memory regions and comes with a way to regonize the right PSY-Q SDK by matching the libraries with their signatures.
The decompiler produces noisy but somewhat reliable output.
Paid product. A MIPS decompiler was introduced starting from IDA Pro 7.5. The output looks clean but often over-simplified. Certain instructions are completely absent from the output; this is due to the disassembler outputting pseudo-instructions that combine multiple instructions (such as outputting a pseudo instruction for lw from a lui and lw). You may want to use the psxida plugin. Not recommended other than very specific scenario.
NOTE:: You can get around the truncation by going to "Options->General->Analysis->Processor specific analysis options" and unchecking "Simplify instructions".