The version of FindVcvars.cmake used here is a bit out-of-date and does not support any VS 2019 build.
In particular, I am on VS 1929, which would be added by this PR: scikit-build/cmake-FindVcvars#1
It would also be helpful to update FindVcvars in Slicer proper once the above PR is merged; both on the master and v4.11 branches.