I need your help

In the past (MySQL 5.6/5.6 times) it was possible to compile Percona PAM plugin for MySQL; plus MariaDB plugin was available as well. I even heard about one more PAM plugin, but it wasn’t updated for many years.
Do we have today some PAM/LDAP plugin for MySQL Community 5.7 integration with LDAP?

Yes, there are 2 plugins: auth_pam and auth_pam_compat. More info here https://www.percona.com/doc/percona-server/5.7/management/pam_plugin.html