actually, this should fix it

networking/firewall.mod.nix

@@ -4,11 +4,8 @@
       networking.firewall.enable = true;
       networking.nftables.enable = true;
     })
-    ({lib, config, ...}: lib.mkIf (
-      config.networking.hostName != "aspartame" # open ports for data collection on everything EXCEPT aspartame, as that would be stupid, considering it is literally public facing. TODO: set up prometheus authentication, perhaps with a certificate. -e
-    ) 
-    {
-      networking.firewall = {
+    ({
+      networking.firewall.interfaces.wg0 = {
         allowedTCPPorts = [
           6703
         ];