Do you know https://wokwi.com/ ? I have found support for the -C3, and even Rust development. Although it's online, if you are looking for local stuff I don't know if what they use is available, or if it's a secret sauce.
It's secret sauce. They're sort of working on a commercial offline offering, but tbh I think it's a one man band and I wasn't super impressed with the quality level. Which is a shame because the idea is great.
How hard would it be to add this to qemu, which already supports sifive boards.