Welcome to Vyos! Great to hear your 10G is working as you wanted! 
I think you want DHCP relay - you want DHCP packets on br0 to be forwarded out to the DHCP server on eth0.
https://docs.vyos.io/en/latest/configuration/service/dhcp-relay.html
If you look at the diagram on that page, but replace it’s eth1 with br0 and it’s DHCP server of 10.0.1.4 with the IP address of your DHCP server on eth0, you should be away.