I missed the initial release of SCC (SymbOS C Compiler) in September 2024 by Prevtenet. The version v1.1 just got out today. It's a C compiler, a fork of Alan Cox's brilliant Fuzix Compiler Kit reworked into a complete development toolchain for SymbOS. Currently SCC runs on Windows and cross-compiles binaries for SymbOS, but can also cross-compile itself to run natively (albeit slowly) on SymbOS itself.

You can download SCC v1.1 on Github.