$ pkg info -lx opencl
----------------------

opencl-3.0.8:

        /usr/local/include/CL/cl.h
        /usr/local/include/CL/cl2.hpp
        /usr/local/include/CL/cl_d3d10.h
        /usr/local/include/CL/cl_d3d11.h
        /usr/local/include/CL/cl_dx9_media_sharing.h
        /usr/local/include/CL/cl_dx9_media_sharing_intel.h
        /usr/local/include/CL/cl_egl.h
        /usr/local/include/CL/cl_ext.h
        /usr/local/include/CL/cl_ext_intel.h
        /usr/local/include/CL/cl_gl.h
        /usr/local/include/CL/cl_gl_ext.h
        /usr/local/include/CL/cl_half.h
        /usr/local/include/CL/cl_icd.h
        /usr/local/include/CL/cl_layer.h
        /usr/local/include/CL/cl_platform.h
        /usr/local/include/CL/cl_va_api_media_sharing_intel.h
        /usr/local/include/CL/cl_version.h
        /usr/local/include/CL/opencl.h
        /usr/local/include/CL/opencl.hpp
        /usr/local/share/licenses/opencl-3.0.8/APACHE20
        /usr/local/share/licenses/opencl-3.0.8/LICENSE
        /usr/local/share/licenses/opencl-3.0.8/catalog.mk


$ pkg info opencl
------------------

opencl-3.0.8

Name           : opencl
Version        : 3.0.8
Installed on   : Sat Aug 20 04:38:33 2022 EDT
Origin         : devel/opencl
Architecture   : FreeBSD:13:*
Prefix         : /usr/local
Categories     : devel
Licenses       : APACHE20
Maintainer     : ohartmann@walstatt.org
WWW            : UNKNOWN
Comment        : Open Computing Language (OpenCL) specifications V3.0 (header files)
Annotations    :
        repo_type      : binary
        repository     : FreeBSD
Flat size      : 628KiB
Description    :
OpenCL (Open Computing Language) is an open royalty-free standard
for general purpose parallel programming across CPUs, GPUs and
other processors, giving software developers portable and efficient
access to the power of these heterogeneous processing platforms.

These header are covering OpenCL API 3.0