With GCC 14 released and GCC 15 in its early stage of development, one of the new targets to be introduced for this next compiler version is aarch64-w64-mingw32 for targeting Microsoft Windows on ARM64 platforms.
This support has been a long time coming as can be tracked via this Bugzilla ticket .
Microsoft engineers pulled everything together and as of a short time ago the aarch64-w64-mingw32 target is merged into GCC Git ahead of next year's GCC 15.1 stable release. The open-source LLVM/Clang compiler has already supported Windows on ARM while now the GNU compiler is joining the party too.