Is your feature request related to a problem? Please describe.
In new 18 floors run everyone collects ~100 anima by the end of run. It' so difficult to track and look what happenes even on my anima power list, my friend's list is most worse to track.
By default it sorted by the time you get.

Describe the solution you'd like
I have some solutions for this, how to improve situation.

1. Add sort list:
   a. Sorted by rarity - first Epic - Rare - Green - White
   easy track most sweet anima powers
   b. Sorted by class/covenant - first Class abilities, in the end general.
   good to learn about other classes
   c. If player gets new anima power, and player wants to see it, you can add some star mark at the edge of this anima icon. So when i will open my friend's anima list with filter from "a." or "b." i will see which one is new.

2. Add Favorites and Black lists:
   d. Add function to mark Favorites anima powers, so if someone in party will get one of them - it will be easy to track. Also it help remember which BiS anima powers i have now (it's good if you do your 5th run a in row).
   e. Add function to mark Blacklisted anima powers. For example it's 3% mastery or other stat, which do nothing special and just hold the space on bars.
   Both of "d" and "e" player can add/remove form list with click+shift click+ctrl etc

Additional context
Here is how your addon looks now with 105 (99 in blizzard UI?) anima power for me.
https://imgur.com/a/ov2kpVL

Hi! I've looked at this idea before and considered it but haven't gotten around to implementing it yet. With that being said, I think it's possible to sort by rarity because when we're getting the Anima Powers, there's an inherit "rarity" attribute that is accessed. However, there's no way to identify each individual anima power by covenant unless I get a list of all covenant anima powers by their ID. I'd have to go and look up all of those manually and won't be sure if I've gotten them all since there's 4 covenants for each class with multiple anima powers per covenant/per class. Hiding and blacklisting certain anima powers like Obleron Armaments sounds more doable since there's only a few of those which could be blacklisted. I wouldn't know off of the top of my head how to implement a "favorites" list.

As for the image, it's capped right now at 48 unique powers which is 4 more than the default Blizzard frames. I'm not sure why my frame says 105 whereas the blizzard one says 99 (I assume Blizz stops counting at 99??). The goal with the dynamic resizing was to save space on screen when you're playing with multiple party members but I'm actively working on other ways to display anima powers so that they don't have to be sized down so small to fit into the frame like they are now.

Thanks for your suggestion, I'll see how I can implement it and how I can adapt to the new 18 floor runs.

About favorite list - you can add aditional field at top of the list (pick out with the line) and send Favorites anima power there.
By default player has no favorites anima powers. Player use click+modifier to add this anima ID to Favorite list (sharing across account please), and if someone in group (including player) has anything from Favorite list it moves at top.

Like this:
https://imgur.com/a/1EHSZYS
Red - Favorites anima, orange all other stuff. (image №2)

Also i uploaded (image №3) how i see it with current system. Anyway i see some "problem", player may have only 1 Favorite anima, and 1st line will be alsmost empty (like on image №2). But at other side this is how Favorite works, other anima people can blacklist it. Or you can add also horizontal line (image №1)

So, main logic for Favorites is 4 points:

1. Let player quick and eazy add/remove anima powers to Favorite
2. Favorite anima powers always at top of all
3. Somehow make it easy detected by fast look where is favorite zone, and where is other stuff
4. List is same for all account.

UPDATE: i found some of this functions in WA, but your addon is good to look my friends anima.
All WA in Torghast (for inspiration and code review) - https://wago.io/shadowlands-weakauras/pve/torghast
WA i am currently testing - https://wago.io/g9G7WgoRX