Static libraries in openblas-dev are missing.
It seems there are no static libraries in openblas-dev
$ apk info -qL openblas-dev
usr/include/cblas.h
usr/include/f77blas.h
usr/include/lapack.h
usr/include/lapacke.h
usr/include/lapacke_config.h
usr/include/lapacke_mangling.h
usr/include/lapacke_utils.h
usr/include/openblas_config.h
usr/lib/liblapack.so
usr/lib/liblapacke.so
usr/lib/libopenblas.so
usr/lib/libopenblas64_.so
usr/lib/cmake/openblas/OpenBLASConfig.cmake
usr/lib/cmake/openblas/OpenBLASConfigVersion.cmake
usr/lib/pkgconfig/openblas.pc
usr/lib/pkgconfig/openblas64.pc
I don't know much about packaging (in alpine and in general), but let me know if I can help.