各ページの関連ページからランダムに(今までに見たページと被らないように)選んで順番に見れると良いのかな

/** @type {URL[]} */
const urls = [];
/** @type {string} */
let startURL = "";
scrapbox.PageMenu.addItem({
  title: "Random jump in relations",
  onClick: () => {
    if (startURL === "") {
      /** @type {HTMLAnchorElement[]} */
      const cards = shuffle(Array.from(
        document.querySelectorAll(
          "li.relation-label:not(.empty-links) ~ li.page-list-item a",
        )
      ));
      urls.push(
        ...cards.map((a) => new URL(a.href))
      );
      if (urls.length === 0) {
        alert("no items");
        return;
      }
      startURL = location.href;
    }
    if (urls.length === 0) {
      alert("Back to the start page");
      move(startURL);
      startURL = "";
      return;
    }
    move(urls.shift());
  },
});

/** @param {string | URL} url */
function move(url) {
  const a = document.createElement("a");
  a.href = url;
  document.body.append(a);
  a.click();
  a.remove();
}

/** 
 * @template T
 * @param {T[]} array
 * @returns {T[]}
 */
function shuffle(array) {
  let result = [...array];
  for (let i = result.length; 1 < i; i--) {
    const k = Math.floor(Math.random() * i);
    [result[k], result[i - 1]] = [result[i - 1], result[k]];
  }
  return result;
}
