As part of the UK Cyber Essentials Certification it important to have a list of all the clients on your network - to support the known devices and connections to your IT resources.
I'm not sure how this could be integrated into the menus - possibly under, "Tools"?
Many Thanks
Pi-hole's Network overview would display the information you seem to require in a searchable, human readable and directly accessible fashion.
Wouldn't that be sufficient?
Also, exporting that to CSV may quickly age to retirement in networks busy with changing clients.
Generally, Pi-hole would not be the right tool for auditing business networks.
For once, MAC addresses are only observable on the same link, so you won't see MACs of devices connecting e.g through VLANs, virtual interfaces like wireguard, or additional routing equipment.
In addition, Pi-hole would not register any DNS requests from clients that don't use it, and it may not even list those if they would not be connected to the same link.
Also, Pi-hole typically relies on your router's DNS server for local hostnames, and that may keep a whole list of names for a client, of which only one would get stored in Pi-hole, while other routers may not run a DNS server at all.
That said, you can always make use of Pi-hole's Query Database to create CSV exports as you see fit:
sudo pihole-FTL sqlite3 --csv /etc/pihole/pihole-FTL.db "<your SELECT statement here>;"