Create a custom LXC container
This is a guide on how to create a custom LXC container.
download a LXC image from here: https://images.linuxcontainers.org
in particular using the url named: rootfs.tar.xz
Once you have downloaded the image, a fix must be added to make proxmox able to manage network:
mkdir /tmp/fixed-template
cd /tmp/fixed-template
tar -xJf /var/lib/vz/template/cache/debian-13-default_20250829.tar.xz
mkdir -p etc/network
cat <<EOF > etc/network/interfaces
auto lo
iface lo inet loopback
auto eth0
iface eth0 inet dhcp
EOF
tar -cJf /var/lib/vz/template/cache/debian-13-default_20250829.tar.xz *
Then you can use the custom image as you would any other LXC image