When running ./configure --without-gui on Big Sur I get the following error:
checking for boostlib >= 1.58.0 (105800)... configure: We could not detect the boost libraries (version 1.58.0 or higher). If you have a staged boost library (still not installed) please specify $BOOST_ROOT in your environment and do not give a PATH to --with-boost option. If you are sure you have boost installed, then check your version number looking in <boost/version.hpp>. See http://randspringer.de/boost for more documentation.
configure: error: Boost is not available!
I've installed boost with homebrew, as suggested here: https://github.com/bitcoin/bitcoin/blob/master/doc/build-osx.md