Well, according to the Join loops website, Loops federates with Mastodon and Pixelfed only, so you do need to make an account either on Loops or one of those other media sites. Do note that your Masto or Pixelfed instance would need to federate with Loops instances. I wish I could verify but I don't think my Pixelfed instance federates with Loops.video

As for which instance to pick, you can see a list at fedi.db and filter by Loops under the "All Software" drop down menu. Do you want the main popular instance? Do you want to focus on a topic? Do you want to stick with your country? There's not many instances as of now, so maybe stick with the original Loops.video, since you can always migrate later.

Edit: Instance migration isn't available yet, but it's planned on the roadmap for Q3 2026.