Let's try this again just to verify

lib/fudo/initrd-network.nix

@@ -45,10 +45,6 @@ in {
         host-key-pkg = host-keys.${config.instance.hostname};
         host-privkey = builtins.toPath "${host-key-pkg}/ssh_host_ed25519_key";
       in {
-        secrets = {
-          "/var/run/ssh-host-key" = host-privkey;
-        };
-
         network = {
           enable = true;
 
@@ -61,7 +57,7 @@ in {
             port = 22;
             authorizedKeys = admin-ssh-keys;
             hostKeys = [
-              "/var/run/ssh-host-key"
+              host-privkey
             ];
           };
         };