And at https://github.com/efabless/caravel_board/tree/main/firmware/chipignite#readme there is a link for installing a toolchain for Linux: https://github.com/riscv/riscv-gnu-toolchain Going to the latest release (2024.09.03) there are dozens of assets? Which one should be used? riscv32-elf-ubuntu-20.04-gcc-nightly-2024.09.03-nightly.tar.gz? risc64? elf or glibc? gcc or llvm?

You'll be installing a cross-compiler; the risc version needs to correspond to what the chip uses. So it will be riscv32i, elf, gcc. I usually like to follow the clear instructions given by Claire Wolf for the picorv32 in https://github.com/yosyshq/picorv32. Just note that the riscv version used by the VexRISC is riscv32i (not riscv32imc or other RISCV extensions, which can be supported by the picorv32).