Allow extensions in incognito home manager chromium

I am adding vimium to chromium in nixos using home manager. I have been able to add an extension, but I am yet to understand how you can customize it. How could I change scroll step size to 120 px, or allow it in incognito mode by default? This is my current chromium.nix:

{ pkgs, ... }:
 programs = {
    chromium = {
      enable = true;
      package = pkgs.chromium;
      extensions = [
        { id = "dbepggeogbaibhgnhhndojpepiihcmeb"; }

I was wondering the same. Did you find a solution @heremoh820 ?

Chromium policy doesn’t include an option to change scroll step read chromium manual for that, though you could set to open in incognito window by default using programs.chromium.commandLineArgs