The links below detail how to setup docker and then run pihole as a container using MacVlan mode.
https://drfrankenstein.co.uk/pi-hole-in-container-manager-on-a-synology-nas/
https://drfrankenstein.co.uk/step-2-setting-up-a-restricted-docker-user-and-obtaining-ids/
Pihole https://github.com/pi-hole/docker-pi-hole/?tab=readme-ov-file#running-pi-hole-docker