You can dedicate a NIC network interface card to a specific LXD container, using nic=physical.
See, for example, Second NIC inside lxd
Of course, you cannot dedicate eth0 to a container unless you are happy with the host losing network connectivity (LXD would not work).
You can also use macvlan interfaces, one for each of eth0 and eth1, and have containers to connect through either and get a DHCP lease from the network. If you really want static IPs, you can do that as well. I describe that in my tutorials, or you can search in this forum as well.
The error message in the title is probably something else, either the NIC is not configured or it has a netmask of 10.255.255.255.