To be fair, that is referring to the mainline gcc project, and not distributions like mingw. And, "partial" support is pretty ambiguous, so it takes a lot more digging to know what kind of support mingw64 12.2.0 has for modules.
Here is my gcc/g++ https://winlibs.com/
I have 12.2, but I see I should update.
No problem using -std=c++20
These winlib for mingw are very easy to use.
You can put the bin folder on path if you like to have immediate access to the binaries.
Nothing to install and no registry changes for these, just the barebone compilers.
No need to define include directories whereabouts or config files.
If you use third party dll's or static libs then the switch -L(path to libs) find them.