If somebody wants to test the WRT3200ACM build that has CPU frequency scaling enabled, it can be found here, including all source code modifications. The build includes the same packages as my R7800 and WNDR3700 community builds.
master-r14935-95b0751d0f-20201113
I am not going to start one more community build for the device series, but may post test builds every now and then.