It looks we can set GRPC_SSL_TARGET_NAME_OVERRIDE_ARG using CreateCustomChannel but it would be also good to have option to completely skip name verification

grpc::ChannelArguments args;

args.SetSslTargetNameOverride("alias.namespace.svc.cluster.local");

args.SetString(GRPC_SSL_TARGET_NAME_OVERRIDE_ARG, "alias.namespace.svc.cluster.local");

grpc::CreateCustomChannel(addr + ":" + port, channel_creds, args);