There definitely is one [1], albeit perhaps not as large and active as the homebrew communities for 8/16 bit consoles (which benefit from low-code tools such as GB Studio and the ability to sell physical game cartridges that do not require modchips) or more modern ones (which tend to have a much lower barrier to entry, given the better specs and availability of SDL ports and whatnot). It is definitely growing though, as I'm seeing more and more people get interested in developing for the PS1.

[1]: https://psx.dev/