try to get vm-variant to use microvm?

vm-variant.nix

@@ -4,13 +4,6 @@ _: {
     # virtualisation.diskImage = null;
     # Boot with tmpfs as root
 
-    fileSystems."/" = {
-      fsType = "tmpfs";
-      options = [
-        "defaults"
-        "size=1024M"
-      ];
-    };
     virtualisation = {
 
       forwardPorts = [
@@ -22,6 +15,8 @@ _: {
       ];
       graphics = false; # disables graphical output
       memorySize = 1024;
+      diskImage = null;
+      # qemu.options = [ "-M microvm,x-option-roms=off,pit=off,pic=on,isa-serial=off" ];
     };
     services.getty = {
       autologinUser = "root";