Is it possible to install lxd on xcp-ng?
It is possible to add repos for Cent OS and EPEL (https://fedoraproject.org/wiki/EPEL).
Try to search for it.
I only see lxc in the EPEL repo so far.
Fedora packages might be compatible, but CentOS might have outdated dependencies (https://serverfault.com/questions/71299/installing-fedora-rpms-in-centos).
You could also try to compile it for CentOS.