(This assumes a working MSYS2 setup, which I haven't yet written a note on. It's not that difficult though.)

Sources:

• Compile QEMU from source on Windows 11
• Allow mklink for a non-admin user

You need to install a couple of support packages:

pacman -Su
pacman -S base-devel git python ninja python-setuptools
pacman -S mingw-w64-x86_64-glib2 mingw-w64-x86_64-pixman
pacman -S mingw-w64-x86_64-gtk3 mingw-w64-x86_64-SDL2 mingw-w64-x86_64-libslirp

In a command prompt (Win-R, cmd), enter start ms-settings:developers. Enable developer mode. (Necessary since the build process needs to be able to make symbolic links.)