It is not impossible, but the situation is that dd-wrt devs are still trying to understand wireguard, your setup may require more changes with the constantly changing web UI for wireguard on dd-wrt.
Have a look at these links
https://github.com/wuruxu/wireguard-ddwrt
https://giuliomagnifico.medium.com/wireguard-vpn-tunnel-on-dd-wrt-router-with-dynamic-ip-25ea3a0cd3a9