Also checking with gcc: get the following messages:

Failed to build these modules:
_ssl

Could not build the ssl module!
Python requires an OpenSSL 1.0.2 or 1.1 compatible libssl with X509_VERIFY_PARAM_set1_host().
LibreSSL 2.6.4 and earlier do not provide the necessary APIs, https://github.com/libressl-portable/portable/issues/381

messages:
building '_ssl' extension
gcc -pthread -Wno-unused-result -Wsign-compare -g -Og -Wall -std=c99 -Wextra -Wno-unused-result -Wno-unused-parameter -Wno-missing-field-initializers -Werror=implicit-function-declaration -fvisibility=hidden -I./Include/internal -I/opt/aixtools/include -I./Include -I. -I/home/aixtools/python/cpython-master/Include -I/home/aixtools/python/cpython-master -c /home/aixtools/python/cpython-master/Modules/_ssl.c -o build/temp.aix-7200-1543-32-3.9-pydebug/home/aixtools/python/cpython-master/Modules/_ssl.o
In file included from /home/aixtools/python/cpython-master/Modules/_ssl.c:136:0:
/home/aixtools/python/cpython-master/Modules/_ssl_data.h:650:28: error: 'ERR_LIB_ASYNC' undeclared here (not in a function); did you mean 'ERR_LIB_ASN1'?
     {"FAILED_TO_SET_POOL", ERR_LIB_ASYNC, 101},
                            ^~~~~~~~~~~~~
                            ERR_LIB_ASN1
/home/aixtools/python/cpython-master/Modules/_ssl_data.h:1510:29: error: 'ERR_LIB_CT' undeclared here (not in a function); did you mean 'ERR_LIB_CMS'?
     {"BASE64_DECODE_ERROR", ERR_LIB_CT, 108},
                             ^~~~~~~~~~
                             ERR_LIB_CMS
/home/aixtools/python/cpython-master/Modules/_ssl_data.h:2650:24: error: 'ERR_LIB_KDF' undeclared here (not in a function); did you mean 'ERR_LIB_BUF'?
     {"INVALID_DIGEST", ERR_LIB_KDF, 100},
                        ^~~~~~~~~~~
                        ERR_LIB_BUF