(untested) config for stinky and diff script.

common/global/default.nix

@@ -5,6 +5,7 @@
     ./console.nix
     ./cpufreq.nix
     ./flakes.nix
+    ./impermanence-options.nix
     ./kernel.nix
     ./locale.nix
     ./network.nix

common/global/impermanence-options.nix

@@ -0,0 +1,14 @@
+{
+  lib,
+  ...
+}:
+{
+  # Define impermanence options that need to be available to all modules
+  # The actual impermanence implementation is in common/impermanence.nix or common/impermanence-tmpfs.nix
+
+  options.custom.impermanence.persistPath = lib.mkOption {
+    type = lib.types.str;
+    default = "/persist";
+    description = "Path where persistent data is stored (e.g., /persist for btrfs, /nix/persist for tmpfs)";
+  };
+}

common/global/network.nix

@@ -1,4 +1,4 @@
-{ lib, ... }:
+{ lib, config, ... }:
 {
   networking = {
     useDHCP = true;
@@ -10,7 +10,7 @@
     '';
   };
 
-  environment.persistence."/persist" = {
+  environment.persistence.${config.custom.impermanence.persistPath} = {
     directories = [ "/var/db/dhcpcd" ];
   };
 }

common/global/tailscale.nix

@@ -22,6 +22,6 @@ in
   config = mkIf cfg.enable {
     services.tailscaleAutoconnect.enable = true;
     services.tailscale.package = pkgs.unstable.tailscale;
-    environment.persistence."/persist".directories = [ "/var/lib/tailscale" ];
+    environment.persistence.${config.custom.impermanence.persistPath}.directories = [ "/var/lib/tailscale" ];
   };
 }