If you read the documentation of the circe module of doom emacs there is a whole paragraph on how to set it up with pass (there is a pass module in doom emacs), but it doesn't mention anything about howto setup up pass itself (of course the doom emacs documentation doesn't, because that isn't the scope of the documentation, to explain how every UNIX tool is set up), but alas! I will try to explain it here.

Installing pass

First of we need pass. Because i use NixOS i will try to explain how i installed it through configuration.nix (you also need gnugpg). This is a sample configuration.nix file

{ pkgs, ... }: {
  environment.systemPackages = with pkgs; [
    pass
    gnupg
  ];

  programs.gnupg.agent = {
    enable = true;
    pinentryFlavor = "gnome3";
    enableSSHSupport = true;
  };

}

build and switch your configuration, and you are good to go.

Configuring pass and a gpg key

First you need to generate a gpg key by running gpg --gen-key, then you need to setup pass by running pass init <your_email>, fill out the form. Easy!

Adding an username and a password

Now to the fun part: inserting a username and a password to be used in your circe configuration. To do this, we need to insert a multiline entry into pass, with the following structure

mysecretpassword
username: myusername

to do so, use: pass insert -m irc/myircserver, then you will drop into a simple editor, when done: type CTRL+D, and pass will save it. The path is up to you, i just chose irc/myircserver but it could be anything.

Now you can use this when configuring circe.

Configuring circe

You need to do the configuration after circe is loaded

(after! circe
(set-irc-server! "irc.libera.chat"
  `(:tls t
    :port 6697
    :nick "doom"
    :sasl-username ,(+pass-get-user "irc/myircserver")
    :sasl-password (lambda (&rest _) (+pass-get-secret "irc/myircserver"))
    :channels ("#emacs")))

if the server you are connecting to, doesn't use SASL then you can use :pass and :user instead of :sasl-username and :sasl-password.

And that's it!! You can now connect to IRC from doom emacs and don't be afraid that you ever expose your credentials when sharing your emacs config. Yay! Evil!!