I made a little thing to more easily move to another instance:

A way to quickly grab a list of your subscribed communities.

Go to your list of subscribed communities, <yourinstance>/communities/listing_type/Subscribed/page/1 and create a bookmark with the following code as link:

code 
javascript:(function() {
    const currentHostname = window.location.hostname;
    const table = document.getElementById('community_table');
    const anchorTags = table.getElementsByTagName('a');
    const communityUrls = [];

    for (let i = 0; i < anchorTags.length; i++) {
      const title = anchorTags[i].title.substring(1);
      const parts = title.split('@');
      const community = parts[0].trim();
      const domain = parts[1] ? parts[1].trim() : currentHostname;
      const communityUrl = `https://${domain}/c/${community}`;
      communityUrls.push(communityUrl);
    }

    const urlsText = communityUrls.join('\n');

    navigator.clipboard.writeText(urlsText)
      .then(() => {
        alert('Community URLs copied to clipboard!');
      })
      .catch((error) => {
        alert('Failed to copy Community URLs to clipboard:', error);
      });
})();

Clicking this bookmark will automatically copy a list of all your subscribed communities and format the links so that you can pop them in the search bar of another instance to subscribe to them from another account.

It can only scrape what’s on screen, so if your subscribed communities list is several pages long just click the bookmark for each page.