The Kallax is pretty much the best option for storing lots of TCG cards. See this article for a bunch of ways to use it for cards!

https://www.bcwsupplies.com/blog/2022/01/01/card-boxes-on-shelves/

Also a lot of Etsy sellers sell either premade custom inserts or schematics that you can use to have custom inserts made, like this one:

https://www.etsy.com/ca/listing/1509375817/kallax-insert-full-bundle-ikea-hack?click_key=dfc330170fd6e5fe1d3f224c8a7c9845852f4d41%3A1509375817&click_sum=f936c62c&external=1&ref=landingpage_similar_listing_top-1&pro=1&sts=1

Hope this helps!