But GRPC is not possible right no if I check the Nutshell code. I can only see LndRest. Are you not running the main version? Thanks!
https://github.com/cashubtc/nutshell/blob/f4621345f38b62ac1a65deadb57c4462bf5c26d0/.env.example#L59 

 I meant LNbits <> LND comm.