Here are the names of some of the distributions that use APT:
Debian GNU/Linux (https://www.debian.org) - it was for this distribution that APT was developed
https://www.debian.org
Conectiva (https://www.conectiva.com.br) - this was the first distribution to port APT for use with rpm
https://www.conectiva.com.br
Libranet (https://www.libranet.com)
https://www.libranet.com
Mandrake (https://www.mandrake.com)
https://www.mandrake.com
PLD (https://www.pld.org.pl)
https://www.pld.org.pl
Vine (https://www.vinelinux.org)
https://www.vinelinux.org
APT4RPM (https://apt4rpm.sf.net)
https://apt4rpm.sf.net
Alt Linux (https://www.altlinux.ru/)
https://www.altlinux.ru/
Red Hat (https://www.redhat.com/)
https://www.redhat.com/
Sun Solaris (https://www.sun.com/)
https://www.sun.com/
SuSE (https://www.suse.de/)
https://www.suse.de/
Yellow Dog Linux (https://www.yellowdoglinux.com/)
https://www.yellowdoglinux.com/