The tooling people have - as of about a year ago said they are ready. Now everyone who considers themselves early adopters is using then. Most are waiting for the early adopters to figure out what the best practices are so we don't make a mess

What early adopters are using them? Because my impression is the tooling still isn’t there

People using Visual C++ with MSBuild, or clang with CMake and ninja.

CMake says they are there. Other tools mostly are not.

Nobody has said they are using them in anything important, but hopefully that is coming.

CMake has support for named modules but does not support header units or C++23 module features such as import std;

Import std has been there for a while but is experimental until gcc supports it. Gcc just for that support so it should be mainline soon.