Credit to: @shabegom - Add a block ref to the current line by adding a ^uniqueId on the end and copying to the clipboard the embed reference link so you can quickly paste the block ref somewhere else in your vault. Similar to Roam ctrl + click and drag to create block ref.

obsidian.templater.create-and-copy-block-ref-id.js

<%*
//v1.1: Changed to using the new "view.editor" instead of deprecated "view.sourceMode.cmEditor"

let cmEditorAct = this.app.workspace.activeLeaf.view.editor;
let curLine = cmEditorAct.getCursor().line;
cmEditorAct.setSelection({ line: curLine, ch: 0 }, { line: curLine, ch: 9999 });

function createBlockHash() {
    let result = '';
    var characters = 'abcdefghijklmnopqrstuvwxyz0123456789';
    var charactersLength = characters.length;
    for ( var i = 0; i < 7; i++ ) {
        result += characters.charAt(Math.floor(Math.random() * charactersLength));
    }
    return result;
}

let id = createBlockHash();
let block = `![[${tp.file.title}#^${id}]]`.split("\n").join("");
navigator.clipboard.writeText(block).then(text => text);
tR = tp.file.selection() + ` ^${id}`.split("\n").join("");
%>

Hello, I found this template recently and decided to add a regex to simply copy the block when it already has a reference. Leaving it here in case anyone find it useful.
I ended up following shabegom guide so I will leave it here as reference for those that are writing scripts directly on the template file. https://shbgm.ca/blog/obsidian/how-to-use-templater-js-scripts

function createAndCopyBlockRefId(tp){
  const editor = app.workspace.activeLeaf.view.editor
  const cursorLine = editor.getCursor().line
    
  editor.setSelection({line: cursorLine, ch: 0}, {line: cursorLine, ch: Infinity})

  const textBlock = tp.file.selection();
  const regex = /\^[a-zA-Z0-9-]+(?!.*\^[a-zA-Z0-9]+)$/

  const match = textBlock.match(regex);

  const id = match ? match[0] :  `^${createBlockHash()}` ;
  const block = `![[${tp.file.title}#${id}]]`.split("\n").join("");

  navigator.clipboard.writeText(block).then(text => text);
  return textBlock +  (match ? '' : `^${id}`.split("\n").join(""));
}

function createBlockHash() {
    let result = '';
    var characters = 'abcdefghijklmnopqrstuvwxyz0123456789';
    var charactersLength = characters.length;
    for ( var i = 0; i < 7; i++ ) {
        result += characters.charAt(Math.floor(Math.random() * charactersLength));
    }
    return result;
}

module.exports = createAndCopyBlockRefId